Apparatus for transmitting broadcast signals, apparatus for receiving broadcast signals, method for transmitting broadcast signals and method for receiving broadcast signals

ABSTRACT

The present invention provides an apparatus of transmitting broadcast signals. The apparatus includes, an encoder encoding service data, a constellation mapper mapping the encoded service data by either QAM, NUQ (Non Uniform QAM) or NUC (Non Uniform Constellation), a mapper mapping the mapped service data into a plurality of OFDM (Orthogonal Frequency Division Multiplex) symbols to build at least one signal frame, a modulator modulating data in the built at least one signal frame by an OFDM scheme and a transmitter transmitting the broadcast signals having the modulated data.

This application claims the benefit of U.S. Provisional PatentApplication No. 61/931,668 filed on Jan. 26, 2014, 61/939,693 filed onFeb. 13, 2014, 61/939,697 filed on Feb. 13, 2014, 61/939,698 filed onFeb. 13, 2014, 61/939,701 filed on Feb. 13, 2014, 61/939,703 filed onFeb. 13, 2014, 61/939,705 filed on Feb. 13, 2014, 61/939,708 filed onFeb. 13, 2014, 61/939,711 filed on Feb. 13, 2014 and 61/939,712 filed onFeb. 13, 2014 which is hereby incorporated by reference as if fully setforth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an apparatus for transmitting broadcastsignals, an apparatus for receiving broadcast signals and methods fortransmitting and receiving broadcast signals.

2. Discussion of the Related Art

As analog broadcast signal transmission comes to an end, varioustechnologies for transmitting/receiving digital broadcast signals arebeing developed. A digital broadcast signal may include a larger amountof video/audio data than an analog broadcast signal and further includevarious types of additional data in addition to the video/audio data.

That is, a digital broadcast system can provide HD (high definition)images, multi-channel audio and various additional services. However,data transmission efficiency for transmission of large amounts of data,robustness of transmission/reception networks and network flexibility inconsideration of mobile reception equipment need to be improved fordigital broadcast.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to an apparatus fortransmitting broadcast signals and an apparatus for receiving broadcastsignals for future broadcast services and methods for transmitting andreceiving broadcast signals for future broadcast services.

An object of the present invention is to provide an apparatus and methodfor transmitting broadcast signals to multiplex data of a broadcasttransmission/reception system providing two or more different broadcastservices in a time domain and transmit the multiplexed data through thesame RF signal bandwidth and an apparatus and method for receivingbroadcast signals corresponding thereto.

Another object of the present invention is to provide an apparatus fortransmitting broadcast signals, an apparatus for receiving broadcastsignals and methods for transmitting and receiving broadcast signals toclassify data corresponding to services by components, transmit datacorresponding to each component as a data pipe, receive and process thedata

Still another object of the present invention is to provide an apparatusfor transmitting broadcast signals, an apparatus for receiving broadcastsignals and methods for transmitting and receiving broadcast signals tosignal signaling information necessary to provide broadcast signals.

To achieve the object and other advantages and in accordance with thepurpose of the invention, as embodied and broadly described herein, thepresent invention provides a method of transmitting broadcast signals.The method of transmitting broadcast signals includes encoding servicedata, mapping the encoded service data by either QAM, NUQ (Non UniformQAM) or NUC (Non Uniform Constellation), mapping the mapped service datainto a plurality of OFDM (Orthogonal Frequency Division Multiplex)symbols to build at least one signal frame, modulating data in the builtat least one signal frame by an OFDM scheme and transmitting thebroadcast signals having the modulated data.

The present invention can achieve transmission flexibility bytransmitting various broadcast services through the same RF signalbandwidth.

The present invention can improve data transmission efficiency andincrease robustness of transmission/reception of broadcast signals usinga MIMO system.

According to the present invention, it is possible to provide broadcastsignal transmission and reception methods and apparatus capable ofreceiving digital broadcast signals without error even with mobilereception equipment or in an indoor environment.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the invention andtogether with the description serve to explain the principle of theinvention. In the drawings:

FIG. 1 illustrates a structure of an apparatus for transmittingbroadcast signals for future broadcast services according to anembodiment of the present invention.

FIG. 2 illustrates an input formatting block according to one embodimentof the present invention.

FIG. 3 illustrates an input formatting block according to anotherembodiment of the present invention.

FIG. 4 illustrates an input formatting block according to anotherembodiment of the present invention.

FIG. 5 illustrates a BICM block according to an embodiment of thepresent invention.

FIG. 6 illustrates a BICM block according to another embodiment of thepresent invention.

FIG. 7 illustrates a frame building block according to one embodiment ofthe present invention.

FIG. 8 illustrates an OFDM generation block according to an embodimentof the present invention.

FIG. 9 illustrates a structure of an apparatus for receiving broadcastsignals for future broadcast services according to an embodiment of thepresent invention.

FIG. 10 illustrates a frame structure according to an embodiment of thepresent invention.

FIG. 11 illustrates a signaling hierarchy structure of the frameaccording to an embodiment of the present invention.

FIG. 12 illustrates preamble signaling data according to an embodimentof the present invention.

FIG. 13 illustrates PLS1 data according to an embodiment of the presentinvention.

FIG. 14 illustrates PLS2 data according to an embodiment of the presentinvention.

FIG. 15 illustrates PLS2 data according to another embodiment of thepresent invention.

FIG. 16 illustrates a logical structure of a frame according to anembodiment of the present invention.

FIG. 17 illustrates PLS mapping according to an embodiment of thepresent invention.

FIG. 18 illustrates EAC mapping according to an embodiment of thepresent invention.

FIG. 19 illustrates FIC mapping according to an embodiment of thepresent invention.

FIG. 20 illustrates a type of DP according to an embodiment of thepresent invention.

FIG. 21 illustrates DP mapping according to an embodiment of the presentinvention.

FIG. 22 illustrates an FEC structure according to an embodiment of thepresent invention.

FIG. 23 illustrates a bit interleaving according to an embodiment of thepresent invention.

FIG. 24 illustrates a cell-word demultiplexing according to anembodiment of the present invention.

FIG. 25 illustrates a time interleaving according to an embodiment ofthe present invention.

FIG. 26 illustrates the basic operation of a twisted row-column blockinterleaver according to an embodiment of the present invention.

FIG. 27 illustrates an operation of a twisted row-column blockinterleaver according to another embodiment of the present invention.

FIG. 28 illustrates a diagonal-wise reading pattern of a twistedrow-column block interleaver according to an embodiment of the presentinvention.

FIG. 29 illustrates interlaved XFECBLOCKs from each interleaving arrayaccording to an embodiment of the present invention.

FIG. 30 illustrates a constellation mapper according to one embodimentof the present invention.

FIG. 31 illustrates a method for configuring an optimum constellationaccording to one embodiment of the present invention.

FIG. 32 illustrates a method for configuring an optimum constellationaccording to another embodiment of the present invention.

FIG. 33 illustrates creation of non-uniform constellations (NUCs)according to one embodiment of the present invention.

FIG. 34 shows an equation for bit allocation according to one embodimentof the present invention.

FIG. 35 illustrates created 16 NUCs and the bits allocated theretoaccording to one embodiment of the present invention.

FIG. 36 shows the parameters of 16 NUCs created according to oneembodiment of the present invention.

FIG. 37 shows constellations for the respective SNRs based on theparameters of the 16 NUCs created according to one embodiment of thepresent invention.

FIG. 38 shows graphs for comparing the BICM capacities of 16 NUCscreated according to one embodiment of the present invention.

FIG. 39 shows some of 64 NUCs created according to one embodiment of thepresent invention and bits allocated thereto.

FIG. 40 shows the others of 64 NUCs created according to one embodimentof the present invention and bits allocated thereto.

FIG. 41 shows constellations for the respective SNRs based on theparameters of the 64 NUCs created according to one embodiment of thepresent invention.

FIG. 42 shows graphs for comparing the BICM capacities of 64 NUCscreated according to one embodiment of the present invention.

FIG. 43 shows some of 256 NUCs created according to one embodiment ofthe present invention and bits allocated thereto.

FIG. 44 shows others of 256 NUCs created according to one embodiment ofthe present invention and bits allocated thereto.

FIG. 45 shows others of 256 NUCs created according to one embodiment ofthe present invention and bits allocated thereto.

FIG. 46 shows the others of 256 NUCs created according to one embodimentof the present invention and bits allocated thereto.

FIG. 47 shows constellations for the respective SNRs based on theparameters of the 256 NUCs created according to one embodiment of thepresent invention.

FIG. 48 shows graphs for comparing the BICM capacities of 256 NUCscreated according to one embodiment of the present invention.

FIG. 49 shows some of 1024 NUCs created according to one embodiment ofthe present invention and bits allocated thereto.

FIG. 50 shows others of 1024 NUCs created according to one embodiment ofthe present invention and bits allocated thereto.

FIG. 51 shows others of 1024 NUCs created according to one embodiment ofthe present invention and bits allocated thereto.

FIG. 52 shows others of 1024 NUCs created according to one embodiment ofthe present invention and bits allocated thereto.

FIG. 53 shows others of 1024 NUCs created according to one embodiment ofthe present invention and bits allocated thereto.

FIG. 54 shows others of 1024 NUCs created according to one embodiment ofthe present invention and bits allocated thereto.

FIG. 55 shows others of 1024 NUCs created according to one embodiment ofthe present invention and bits allocated thereto.

FIG. 56 shows others of 1024 NUCs created according to one embodiment ofthe present invention and bits allocated thereto.

FIG. 57 shows others of 1024 NUCs created according to one embodiment ofthe present invention and bits allocated thereto.

FIG. 58 shows the others of 1024 NUCs created according to oneembodiment of the present invention and bits allocated thereto.

FIG. 59 shows constellations for the respective SNRs based on theparameters of the 1024 NUCs created according to one embodiment of thepresent invention.

FIG. 60 shows graphs for comparing the BICM capacities of 1024 NUCscreated according to one embodiment of the present invention.

FIG. 61 shows a constellation of 16 NUCs for 5/15 code rate andcoordinates of the respective constellations of 16 NUCs for 5/15 coderate according to an embodiment of the present invention.

FIG. 62 shows a constellation of 16 NUCs for 6/15 code rate andcoordinates of the respective constellations of 16 NUCs for 6/15 coderate according to an embodiment of the present invention.

FIG. 63 shows a constellation of 16 NUCs for 7/15 code rate andcoordinates of the respective constellations of 16 NUCs for 7/15 coderate according to an embodiment of the present invention.

FIG. 64 shows a constellation of 16 NUCs for 8/15 code rate andcoordinates of the respective constellations of 16 NUCs for 8/15 coderate according to an embodiment of the present invention.

FIG. 65 shows a constellation of 16 NUCs for 9/15 code rate andcoordinates of the respective constellations of 16 NUCs for 9/15 coderate according to an embodiment of the present invention.

FIG. 66 shows a constellation of 16 NUCs for 10/15 code rate andcoordinates of the respective constellations of 16 NUCs for 10/15 coderate according to an embodiment of the present invention.

FIG. 67 describes a process of mapping IQ-balanced/IQ-symmetricnon-uniform constellations according to one embodiment of the presentinvention.

FIG. 68 shows constellations of 64 NUCs at the SNR of 18 dB using themethod of IQ-balanced non-uniform constellation mapping according to oneembodiment of the present invention.

FIG. 69 shows a constellation and the coordinates of the constellationsof 16 NUCs for 11/15 code rate based on the IQ-balanced non-uniformconstellation mapping method according to an embodiment of the presentinvention.

FIG. 70 shows a constellation and the coordinates of the constellationsof 16 NUCs for 12/15 code rate based on the IQ-balanced non-uniformconstellation mapping method according to an embodiment of the presentinvention.

FIG. 71 shows a constellation and the coordinates of the constellationsof 16 NUCs for 13/15 code rate based on the IQ-balanced non-uniformconstellation mapping method according to an embodiment of the presentinvention.

FIG. 72 is a view illustrating 2-dimensional constellations according toan embodiment of the present invention.

FIG. 73 is a view illustrating decision planes of Non-uniformconstellation according to an embodiment of the present invention.

FIG. 74 is a chart illustrating BICM capacity in a constellation mappingAWGN environment according to an embodiment of the present invention.

FIG. 75 is a flowchart illustrating a method for transmitting broadcastsignals according to an embodiment of the present invention.

FIG. 76 is a flowchart illustrating a method for receiving broadcastsignals according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. The detailed description, which will be given below withreference to the accompanying drawings, is intended to explain exemplaryembodiments of the present invention, rather than to show the onlyembodiments that can be implemented according to the present invention.The following detailed description includes specific details in order toprovide a thorough understanding of the present invention. However, itwill be apparent to those skilled in the art that the present inventionmay be practiced without such specific details.

Although most terms used in the present invention have been selectedfrom general ones widely used in the art, some terms have beenarbitrarily selected by the applicant and their meanings are explainedin detail in the following description as needed. Thus, the presentinvention should be understood based upon the intended meanings of theterms rather than their simple names or meanings.

The present invention provides apparatuses and methods for transmittingand receiving broadcast signals for future broadcast services. Futurebroadcast services according to an embodiment of the present inventioninclude a terrestrial broadcast service, a mobile broadcast service, aUHDTV service, etc. The present invention may process broadcast signalsfor the future broadcast services through non-MIMO (Multiple InputMultiple Output) or MIMO according to one embodiment. A non-MIMO schemeaccording to an embodiment of the present invention may include a MISO(Multiple Input Single Output) scheme, a SISO (Single Input SingleOutput) scheme, etc.

While MISO or MIMO uses two antennas in the following for convenience ofdescription, the present invention is applicable to systems using two ormore antennas.

The present invention may defines three physical layer (PL)profiles—base, handheld and advanced profiles—each optimized to minimizereceiver complexity while attaining the performance required for aparticular use case. The physical layer (PHY) profiles are subsets ofall configurations that a corresponding receiver should implement.

The three PHY profiles share most of the functional blocks but differslightly in specific blocks and/or parameters. Additional PHY profilescan be defined in the future. For the system evolution, future profilescan also be multiplexed with the existing profiles in a single RFchannel through a future extension frame (FEF). The details of each PHYprofile are described below.

1. Base Profile

The base profile represents a main use case for fixed receiving devicesthat are usually connected to a roof-top antenna. The base profile alsoincludes portable devices that could be transported to a place butbelong to a relatively stationary reception category. Use of the baseprofile could be extended to handheld devices or even vehicular by someimproved implementations, but those use cases are not expected for thebase profile receiver operation.

Target SNR range of reception is from approximately 10 to 20 dB, whichincludes the 15 dB SNR reception capability of the existing broadcastsystem (e.g. ATSC A/53). The receiver complexity and power consumptionis not as critical as in the battery-operated handheld devices, whichwill use the handheld profile. Key system parameters for the baseprofile are listed in below table 1.

TABLE 1 LDPC codeword length 16K, 64K bits Constellation size 4~10 bpcu(bits per channel use) Time de-interleaving memory size ≦2¹⁹ data cellsPilot patterns Pilot pattern for fixed reception FFT size 16K, 32Kpoints

2. Handheld Profile

The handheld profile is designed for use in handheld and vehiculardevices that operate with battery power. The devices can be moving withpedestrian or vehicle speed. The power consumption as well as thereceiver complexity is very important for the implementation of thedevices of the handheld profile. The target SNR range of the handheldprofile is approximately 0 to 10 dB, but can be configured to reachbelow 0 dB when intended for deeper indoor reception.

In addition to low SNR capability, resilience to the Doppler Effectcaused by receiver mobility is the most important performance attributeof the handheld profile. Key system parameters for the handheld profileare listed in the below table 2.

TABLE 2 LDPC codeword length 16K bits Constellation size 2~8 bpcu Timede-interleaving memory size ≦2¹⁸ data cells Pilot patterns Pilotpatterns for mobile and indoor reception FFT size 8K, 16K points

3. Advanced Profile

The advanced profile provides highest channel capacity at the cost ofmore implementation complexity. This profile requires using MIMOtransmission and reception, and UHDTV service is a target use case forwhich this profile is specifically designed. The increased capacity canalso be used to allow an increased number of services in a givenbandwidth, e.g., multiple SDTV or HDTV services.

The target SNR range of the advanced profile is approximately 20 to 30dB. MIMO transmission may initially use existing elliptically-polarizedtransmission equipment, with extension to full-power cross-polarizedtransmission in the future. Key system parameters for the advancedprofile are listed in below table 3.

TABLE 3 LDPC codeword length 16K, 64K bits Constellation size 8~12 bpcuTime de-interleaving memory size ≦2¹⁹ data cells Pilot patterns Pilotpattern for fixed reception FFT size 16K, 32K points

In this case, the base profile can be used as a profile for both theterrestrial broadcast service and the mobile broadcast service. That is,the base profile can be used to define a concept of a profile whichincludes the mobile profile. Also, the advanced profile can be dividedadvanced profile for a base profile with MIMO and advanced profile for ahandheld profile with MIMO. Moreover, the three profiles can be changedaccording to intention of the designer.

The following terms and definitions may apply to the present invention.The following terms and definitions can be changed according to design.

auxiliary stream: sequence of cells carrying data of as yet undefinedmodulation and coding, which may be used for future extensions or asrequired by broadcasters or network operators

base data pipe: data pipe that carries service signaling data

baseband frame (or BBFRAME): set of K_(bch) bits which form the input toone FEC encoding process (BCH and LDPC encoding)

cell: modulation value that is carried by one carrier of the OFDMtransmission

coded block: LDPC-encoded block of PLS1 data or one of the LDPC-encodedblocks of PLS2 data

data pipe: logical channel in the physical layer that carries servicedata or related metadata, which may carry one or multiple service(s) orservice component(s).

data pipe unit: a basic unit for allocating data cells to a DP in aframe.

data symbol: OFDM symbol in a frame which is not a preamble symbol (theframe signaling symbol and frame edge symbol is included in the datasymbol)

DP_ID: this 8-bit field identifies uniquely a DP within the systemidentified by the SYSTEM_ID

dummy cell: cell carrying a pseudo-random value used to fill theremaining capacity not used for PLS signaling, DPs or auxiliary streams

emergency alert channel: part of a frame that carries EAS informationdata

frame: physical layer time slot that starts with a preamble and endswith a frame edge symbol

frame repetition unit: a set of frames belonging to same or differentphysical layer profile including a FEF, which is repeated eight times ina super-frame

fast information channel: a logical channel in a frame that carries themapping information between a service and the corresponding base DP

FECBLOCK: set of LDPC-encoded bits of a DP data

FFT size: nominal FFT size used for a particular mode, equal to theactive symbol period T_(s) expressed in cycles of the elementary periodT

frame signaling symbol: OFDM symbol with higher pilot density used atthe start of a frame in certain combinations of FFT size, guard intervaland scattered pilot pattern, which carries a part of the PLS data

frame edge symbol: OFDM symbol with higher pilot density used at the endof a frame in certain combinations of FFT size, guard interval andscattered pilot pattern

frame-group: the set of all the frames having the same PHY profile typein a super-frame.

future extension frame: physical layer time slot within the super-framethat could be used for future extension, which starts with a preamble

Futurecast UTB system: proposed physical layer broadcasting system, ofwhich the input is one or more MPEG2-TS or IP or general stream(s) andof which the output is an RF signal

input stream: A stream of data for an ensemble of services delivered tothe end users by the system.

normal data symbol: data symbol excluding the frame signaling symbol andthe frame edge symbol

PHY profile: subset of all configurations that a corresponding receivershould implement

PLS: physical layer signaling data consisting of PLS1 and PLS2

PLS1: a first set of PLS data carried in the FSS symbols having a fixedsize, coding and modulation, which carries basic information about thesystem as well as the parameters needed to decode the PLS2

NOTE: PLS1 data remains constant for the duration of a frame-group.

PLS2: a second set of PLS data transmitted in the FSS symbol, whichcarries more detailed PLS data about the system and the DPs

PLS2 dynamic data: PLS2 data that may dynamically change frame-by-frame

PLS2 static data: PLS2 data that remains static for the duration of aframe-group

preamble signaling data: signaling data carried by the preamble symboland used to identify the basic mode of the system

preamble symbol: fixed-length pilot symbol that carries basic PLS dataand is located in the beginning of a frame

NOTE: The preamble symbol is mainly used for fast initial band scan todetect the system signal, its timing, frequency offset, and FFT-size.

reserved for future use: not defined by the present document but may bedefined in future

super-frame: set of eight frame repetition units

time interleaving block (TI block): set of cells within which timeinterleaving is carried out, corresponding to one use of the timeinterleaver memory

TI group: unit over which dynamic capacity allocation for a particularDP is carried out, made up of an integer, dynamically varying number ofXFECBLOCKs.

NOTE: The TI group may be mapped directly to one frame or may be mappedto multiple frames. It may contain one or more TI blocks.

Type 1 DP: DP of a frame where all DPs are mapped into the frame in TDMfashion

Type 2 DP: DP of a frame where all DPs are mapped into the frame in FDMfashion

XFECBLOCK: set of N cells cells carrying all the bits of one LDPCFECBLOCK

FIG. 1 illustrates a structure of an apparatus for transmittingbroadcast signals for future broadcast services according to anembodiment of the present invention.

The apparatus for transmitting broadcast signals for future broadcastservices according to an embodiment of the present invention can includean input formatting block 1000, a BICM (Bit interleaved coding &modulation) block 1010, a frame structure block 1020, an OFDM(Orthogonal Frequency Division Multiplexing) generation block 1030 and asignaling generation block 1040. A description will be given of theoperation of each module of the apparatus for transmitting broadcastsignals.

IP stream/packets and MPEG2-TS are the main input formats, other streamtypes are handled as General Streams. In addition to these data inputs,Management Information is input to control the scheduling and allocationof the corresponding bandwidth for each input stream. One or multiple TSstream(s), IP stream(s) and/or General Stream(s) inputs aresimultaneously allowed.

The input formatting block 1000 can demultiplex each input stream intoone or multiple data pipe(s), to each of which an independent coding andmodulation is applied. The data pipe (DP) is the basic unit forrobustness control, thereby affecting quality-of-service (QoS). One ormultiple service(s) or service component(s) can be carried by a singleDP. Details of operations of the input formatting block 1000 will bedescribed later.

The data pipe is a logical channel in the physical layer that carriesservice data or related metadata, which may carry one or multipleservice(s) or service component(s).

Also, the data pipe unit: a basic unit for allocating data cells to a DPin a frame.

In the BICM block 1010, parity data is added for error correction andthe encoded bit streams are mapped to complex-value constellationsymbols. The symbols are interleaved across a specific interleavingdepth that is used for the corresponding DP. For the advanced profile,MIMO encoding is performed in the BICM block 1010 and the additionaldata path is added at the output for MIMO transmission. Details ofoperations of the BICM block 1010 will be described later.

The Frame Building block 1020 can map the data cells of the input DPsinto the OFDM symbols within a frame. After mapping, the frequencyinterleaving is used for frequency-domain diversity, especially tocombat frequency-selective fading channels. Details of operations of theFrame Building block 1020 will be described later.

After inserting a preamble at the beginning of each frame, the OFDMGeneration block 1030 can apply conventional OFDM modulation having acyclic prefix as guard interval. For antenna space diversity, adistributed MISO scheme is applied across the transmitters. In addition,a Peak-to-Average Power Reduction (PAPR) scheme is performed in the timedomain. For flexible network planning, this proposal provides a set ofvarious FFT sizes, guard interval lengths and corresponding pilotpatterns. Details of operations of the OFDM Generation block 1030 willbe described later.

The Signaling Generation block 1040 can create physical layer signalinginformation used for the operation of each functional block. Thissignaling information is also transmitted so that the services ofinterest are properly recovered at the receiver side. Details ofoperations of the Signaling Generation block 1040 will be describedlater.

FIGS. 2, 3 and 4 illustrate the input formatting block 1000 according toembodiments of the present invention. A description will be given ofeach figure.

FIG. 2 illustrates an input formatting block according to one embodimentof the present invention. FIG. 2 shows an input formatting module whenthe input signal is a single input stream.

The input formatting block illustrated in FIG. 2 corresponds to anembodiment of the input formatting block 1000 described with referenceto FIG. 1.

The input to the physical layer may be composed of one or multiple datastreams. Each data stream is carried by one DP. The mode adaptationmodules slice the incoming data stream into data fields of the basebandframe (BBF). The system supports three types of input data streams:MPEG2-TS, Internet protocol (IP) and Generic stream (GS). MPEG2-TS ischaracterized by fixed length (188 byte) packets with the first bytebeing a sync-byte (0x47). An IP stream is composed of variable length IPdatagram packets, as signaled within IP packet headers. The systemsupports both IPv4 and IPv6 for the IP stream. GS may be composed ofvariable length packets or constant length packets, signaled withinencapsulation packet headers.

(a) shows a mode adaptation block 2000 and a stream adaptation 2010 forsignal DP and (b) shows a PLS generation block 2020 and a PLS scrambler2030 for generating and processing PLS data. A description will be givenof the operation of each block.

The Input Stream Splitter splits the input TS, IP, GS streams intomultiple service or service component (audio, video, etc.) streams. Themode adaptation module 2010 is comprised of a CRC Encoder, BB (baseband)Frame Slicer, and BB Frame Header Insertion block.

The CRC Encoder provides three kinds of CRC encoding for error detectionat the user packet (UP) level, i.e., CRC-8, CRC-16, and CRC-32. Thecomputed CRC bytes are appended after the UP. CRC-8 is used for TSstream and CRC-32 for IP stream. If the GS stream doesn't provide theCRC encoding, the proposed CRC encoding should be applied.

BB Frame Slicer maps the input into an internal logical-bit format. Thefirst received bit is defined to be the MSB. The BB Frame Slicerallocates a number of input bits equal to the available data fieldcapacity. To allocate a number of input bits equal to the BBF payload,the UP packet stream is sliced to fit the data field of BBF.

BB Frame Header Insertion block can insert fixed length BBF header of 2bytes is inserted in front of the BB Frame. The BBF header is composedof STUFFI (1 bit), SYNCD (13 bits), and RFU (2 bits). In addition to thefixed 2-Byte BBF header, BBF can have an extension field (1 or 3 bytes)at the end of the 2-byte BBF header.

The stream adaptation 2010 is comprised of stuffing insertion block andBB scrambler.

The stuffing insertion block can insert stuffing field into a payload ofa BB frame. If the input data to the stream adaptation is sufficient tofill a BB-Frame, STUFFI is set to ‘0’ and the BBF has no stuffing field.Otherwise STUFFI is set to ‘1’ and the stuffing field is insertedimmediately after the BBF header. The stuffing field comprises two bytesof the stuffing field header and a variable size of stuffing data.

The BB scrambler scrambles complete BBF for energy dispersal. Thescrambling sequence is synchronous with the BBF. The scrambling sequenceis generated by the feed-back shift register.

The PLS generation block 2020 can generate physical layer signaling(PLS) data. The PLS provides the receiver with a means to accessphysical layer DPs. The PLS data consists of PLS1 data and PLS2 data.

The PLS1 data is a first set of PLS data carried in the FSS symbols inthe frame having a fixed size, coding and modulation, which carriesbasic information about the system as well as the parameters needed todecode the PLS2 data. The PLS1 data provides basic transmissionparameters including parameters required to enable the reception anddecoding of the PLS2 data. Also, the PLS1 data remains constant for theduration of a frame-group.

The PLS2 data is a second set of PLS data transmitted in the FSS symbol,which carries more detailed PLS data about the system and the DPs. ThePLS2 contains parameters that provide sufficient information for thereceiver to decode the desired DP. The PLS2 signaling further consistsof two types of parameters, PLS2 Static data (PLS2-STAT data) and PLS2dynamic data (PLS2-DYN data). The PLS2 Static data is PLS2 data thatremains static for the duration of a frame-group and the PLS2 dynamicdata is PLS2 data that may dynamically change frame-by-frame.

Details of the PLS data will be described later.

The PLS scrambler 2030 can scramble the generated PLS data for energydispersal.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 3 illustrates an input formatting block according to anotherembodiment of the present invention.

The input formatting block illustrated in FIG. 3 corresponds to anembodiment of the input formatting block 1000 described with referenceto FIG. 1.

FIG. 3 shows a mode adaptation block of the input formatting block whenthe input signal corresponds to multiple input streams.

The mode adaptation block of the input formatting block for processingthe multiple input streams can independently process the multiple inputstreams.

Referring to FIG. 3, the mode adaptation block for respectivelyprocessing the multiple input streams can include an input streamsplitter 3000, an input stream synchronizer 3010, a compensating delayblock 3020, a null packet deletion block 3030, a head compression block3040, a CRC encoder 3050, a BB frame slicer 3060 and a BB headerinsertion block 3070. Description will be given of each block of themode adaptation block.

Operations of the CRC encoder 3050, BB frame slicer 3060 and BB headerinsertion block 3070 correspond to those of the CRC encoder, BB frameslicer and BB header insertion block described with reference to FIG. 2and thus description thereof is omitted.

The input stream splitter 3000 can split the input TS, IP, GS streamsinto multiple service or service component (audio, video, etc.) streams.

The input stream synchronizer 3010 may be referred as ISSY. The ISSY canprovide suitable means to guarantee Constant Bit Rate (CBR) and constantend-to-end transmission delay for any input data format. The ISSY isalways used for the case of multiple DPs carrying TS, and optionallyused for multiple DPs carrying GS streams.

The compensating delay block 3020 can delay the split TS packet streamfollowing the insertion of ISSY information to allow a TS packetrecombining mechanism without requiring additional memory in thereceiver.

The null packet deletion block 3030, is used only for the TS inputstream case. Some TS input streams or split TS streams may have a largenumber of null-packets present in order to accommodate VBR (variablebit-rate) services in a CBR TS stream. In this case, in order to avoidunnecessary transmission overhead, null-packets can be identified andnot transmitted. In the receiver, removed null-packets can bere-inserted in the exact place where they were originally by referenceto a deleted null-packet (DNP) counter that is inserted in thetransmission, thus guaranteeing constant bit-rate and avoiding the needfor time-stamp (PCR) updating.

The head compression block 3040 can provide packet header compression toincrease transmission efficiency for TS or IP input streams. Because thereceiver can have a priori information on certain parts of the header,this known information can be deleted in the transmitter.

For Transport Stream, the receiver has a-priori information about thesync-byte configuration (0x47) and the packet length (188 Byte). If theinput TS stream carries content that has only one PID, i.e., for onlyone service component (video, audio, etc.) or service sub-component (SVCbase layer, SVC enhancement layer, MVC base view or MVC dependentviews), TS packet header compression can be applied (optionally) to theTransport Stream. IP packet header compression is used optionally if theinput steam is an IP stream.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 4 illustrates an input formatting block according to anotherembodiment of the present invention.

The input formatting block illustrated in FIG. 4 corresponds to anembodiment of the input formatting block 1000 described with referenceto FIG. 1.

FIG. 4 illustrates a stream adaptation block of the input formattingmodule when the input signal corresponds to multiple input streams.

Referring to FIG. 4, the mode adaptation block for respectivelyprocessing the multiple input streams can include a scheduler 4000, an1-Frame delay block 4010, a stuffing insertion block 4020, an in-bandsignaling 4030, a BB Frame scrambler 4040, a PLS generation block 4050and a PLS scrambler 4060. Description will be given of each block of thestream adaptation block.

Operations of the stuffing insertion block 4020, the BB Frame scrambler4040, the PLS generation block 4050 and the PLS scrambler 4060correspond to those of the stuffing insertion block, BB scrambler, PLSgeneration block and the PLS scrambler described with reference to FIG.2 and thus description thereof is omitted.

The scheduler 4000 can determine the overall cell allocation across theentire frame from the amount of FECBLOCKs of each DP. Including theallocation for PLS, EAC and FIC, the scheduler generate the values ofPLS2-DYN data, which is transmitted as in-band signaling or PLS cell inFSS of the frame. Details of FECBLOCK, EAC and FIC will be describedlater.

The 1-Frame delay block 4010 can delay the input data by onetransmission frame such that scheduling information about the next framecan be transmitted through the current frame for in-band signalinginformation to be inserted into the DPs.

The in-band signaling 4030 can insert un-delayed part of the PLS2 datainto a DP of a frame.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 5 illustrates a BICM block according to an embodiment of thepresent invention.

The BICM block illustrated in FIG. 5 corresponds to an embodiment of theBICM block 1010 described with reference to FIG. 1.

As described above, the apparatus for transmitting broadcast signals forfuture broadcast services according to an embodiment of the presentinvention can provide a terrestrial broadcast service, mobile broadcastservice, UHDTV service, etc.

Since QoS (quality of service) depends on characteristics of a serviceprovided by the apparatus for transmitting broadcast signals for futurebroadcast services according to an embodiment of the present invention,data corresponding to respective services needs to be processed throughdifferent schemes. Accordingly, the a BICM block according to anembodiment of the present invention can independently process DPs inputthereto by independently applying SISO, MISO and MIMO schemes to thedata pipes respectively corresponding to data paths. Consequently, theapparatus for transmitting broadcast signals for future broadcastservices according to an embodiment of the present invention can controlQoS for each service or service component transmitted through each DP.

(a) shows the BICM block shared by the base profile and the handheldprofile and (b) shows the BICM block of the advanced profile.

The BICM block shared by the base profile and the handheld profile andthe BICM block of the advanced profile can include plural processingblocks for processing each DP.

A description will be given of each processing block of the BICM blockfor the base profile and the handheld profile and the BICM block for theadvanced profile.

A processing block 5000 of the BICM block for the base profile and thehandheld profile can include a Data FEC encoder 5010, a bit interleaver5020, a constellation mapper 5030, an SSD (Signal Space Diversity)encoding block 5040 and a time interleaver 5050.

The Data FEC encoder 5010 can perform the FEC encoding on the input BBFto generate FECBLOCK procedure using outer coding (BCH), and innercoding (LDPC). The outer coding (BCH) is optional coding method. Detailsof operations of the Data FEC encoder 5010 will be described later.

The bit interleaver 5020 can interleave outputs of the Data FEC encoder5010 to achieve optimized performance with combination of the LDPC codesand modulation scheme while providing an efficiently implementablestructure. Details of operations of the bit interleaver 5020 will bedescribed later.

The constellation mapper 5030 can modulate each cell word from the bitinterleaver 5020 in the base and the handheld profiles, or cell wordfrom the Cell-word demultiplexer 5010-1 in the advanced profile usingeither QPSK, QAM-16, non-uniform QAM (NUQ-64, NUQ-256, NUQ-1024) ornon-uniform constellation (NUC-16, NUC-64, NUC-256, NUC-1024) to give apower-normalized constellation point, e₁. This constellation mapping isapplied only for DPs. Observe that QAM-16 and NUQs are square shaped,while NUCs have arbitrary shape. When each constellation is rotated byany multiple of 90 degrees, the rotated constellation exactly overlapswith its original one. This “rotation-sense” symmetric property makesthe capacities and the average powers of the real and imaginarycomponents equal to each other. Both NUQs and NUCs are definedspecifically for each code rate and the particular one used is signaledby the parameter DP_MOD filed in PLS2 data.

The SSD encoding block 5040 can precode cells in two (2D), three (3D),and four (4D) dimensions to increase the reception robustness underdifficult fading conditions.

The time interleaver 5050 can operates at the DP level. The parametersof time interleaving (TI) may be set differently for each DP. Details ofoperations of the time interleaver 5050 will be described later.

A processing block 5000-1 of the BICM block for the advanced profile caninclude the Data FEC encoder, bit interleaver, constellation mapper, andtime interleaver. However, the processing block 5000-1 is distinguishedfrom the processing block 5000 further includes a cell-worddemultiplexer 5010-1 and a MIMO encoding block 5020-1.

Also, the operations of the Data FEC encoder, bit interleaver,constellation mapper, and time interleaver in the processing block5000-1 correspond to those of the Data FEC encoder 5010, bit interleaver5020, constellation mapper 5030, and time interleaver 5050 described andthus description thereof is omitted.

The cell-word demultiplexer 5010-1 is used for the DP of the advancedprofile to divide the single cell-word stream into dual cell-wordstreams for MIMO processing. Details of operations of the cell-worddemultiplexer 5010-1 will be described later.

The MIMO encoding block 5020-1 can processing the output of thecell-word demultiplexer 5010-1 using MIMO encoding scheme. The MIMOencoding scheme was optimized for broadcasting signal transmission. TheMIMO technology is a promising way to get a capacity increase but itdepends on channel characteristics. Especially for broadcasting, thestrong LOS component of the channel or a difference in the receivedsignal power between two antennas caused by different signal propagationcharacteristics makes it difficult to get capacity gain from MIMO. Theproposed MIMO encoding scheme overcomes this problem using arotation-based pre-coding and phase randomization of one of the MIMOoutput signals.

MIMO encoding is intended for a 2×2 MIMO system requiring at least twoantennas at both the transmitter and the receiver. Two MIMO encodingmodes are defined in this proposal; full-rate spatial multiplexing(FR-SM) and full-rate full-diversity spatial multiplexing (FRFD-SM). TheFR-SM encoding provides capacity increase with relatively smallcomplexity increase at the receiver side while the FRFD-SM encodingprovides capacity increase and additional diversity gain with a greatcomplexity increase at the receiver side. The proposed MIMO encodingscheme has no restriction on the antenna polarity configuration.

MIMO processing is required for the advanced profile frame, which meansall DPs in the advanced profile frame are processed by the MIMO encoder.MIMO processing is applied at DP level. Pairs of the ConstellationMapper outputs NUQ (e_(1,i) and e_(2,i)) are fed to the input of theMIMO Encoder. Paired MIMO Encoder output (g1,i and g2,i) is transmittedby the same carrier k and OFDM symbol 1 of their respective TX antennas.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 6 illustrates a BICM block according to another embodiment of thepresent invention.

The BICM block illustrated in FIG. 6 corresponds to an embodiment of theBICM block 1010 described with reference to FIG. 1.

FIG. 6 illustrates a BICM block for protection of physical layersignaling (PLS), emergency alert channel (EAC) and fast informationchannel (FIC). EAC is a part of a frame that carries EAS informationdata and FIC is a logical channel in a frame that carries the mappinginformation between a service and the corresponding base DP. Details ofthe EAC and FIC will be described later.

Referring to FIG. 6, the BICM block for protection of PLS, EAC and FICcan include a PLS FEC encoder 6000, a bit interleaver 6010, aconstellation mapper 6020 and time interleaver 6030.

Also, the PLS FEC encoder 6000 can include a scrambler, BCHencoding/zero insertion block, LDPC encoding block and LDPC paritypunturing block. Description will be given of each block of the BICMblock.

The PLS FEC encoder 6000 can encode the scrambled PLS 1/2 data, EAC andFIC section.

The scrambler can scramble PLS1 data and PLS2 data before BCH encodingand shortened and punctured LDPC encoding.

The BCH encoding/zero insertion block can perform outer encoding on thescrambled PLS 1/2 data using the shortened BCH code for PLS protectionand insert zero bits after the BCH encoding. For PLS1 data only, theoutput bits of the zero insertion may be permutted before LDPC encoding.

The LDPC encoding block can encode the output of the BCH encoding/zeroinsertion block using LDPC code. To generate a complete coded block,C_(idpc,) parity bits, P_(ldpc) are encoded systematically from eachzero-inserted PLS information block, I_(ldpc) and appended after it.

C _(ldpc) =[I _(ldpc) P _(ldpc) ]=[i ₀ ,i ₁ , . . . , i _(K) _(ldpc) ₊₁,p ₀ ,p ₁ , . . . , p _(N) _(ldpc) _(-K) _(ldpc) ⁻¹]  [Expression 1]

The LDPC code parameters for PLS1 and PLS2 are as following table 4.

TABLE 4 code Signaling Type K_(sig) K_(bch) N_(bch)_parityK_(ldpc)(=N_(bch)) N_(ldpc) N_(ldpc)_parity rate Q_(ldpc) PLS1 342 102060 1080 4320 3240 ¼ 36 PLS2 <1021 >1020 2100 2160 7200 5040 3/10 56

The LDPC parity punturing block can perform puncturing on the PLS1 dataand PLS 2 data.

When shortening is applied to the PLS1 data protection, some LDPC paritybits are punctured after LDPC encoding. Also, for the PLS2 dataprotection, the LDPC parity bits of PLS2 are punctured after LDPCencoding. These punctured bits are not transmitted.

The bit interleaver 6010 can interleave the each shortened and puncturedPLS1 data and PLS2 data.

The constellation mapper 6020 can map the bit ineterlaeved PLS1 data andPLS2 data onto constellations.

The time interleaver 6030 can interleave the mapped PLS1 data and PLS2data.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 7 illustrates a frame building block according to one embodiment ofthe present invention.

The frame building block illustrated in FIG. 7 corresponds to anembodiment of the frame building block 1020 described with reference toFIG. 1.

Referring to FIG. 7, the frame building block can include a delaycompensation block 7000, a cell mapper 7010 and a frequency interleaver7020. Description will be given of each block of the frame buildingblock.

The delay compensation block 7000 can adjust the timing between the datapipes and the corresponding PLS data to ensure that they are co-timed atthe transmitter end. The PLS data is delayed by the same amount as datapipes are by addressing the delays of data pipes caused by the InputFormatting block and BICM block. The delay of the BICM block is mainlydue to the time interleaver. In-band signaling data carries informationof the next TI group so that they are carried one frame ahead of the DPsto be signaled. The Delay Compensating block delays in-band signalingdata accordingly.

The cell mapper 7010 can map PLS, EAC, FIC, DPs, auxiliary streams anddummy cells into the active carriers of the OFDM symbols in the frame.The basic function of the cell mapper 7010 is to map data cells producedby the TIs for each of the DPs, PLS cells, and EAC/FIC cells, if any,into arrays of active OFDM cells corresponding to each of the OFDMsymbols within a frame. Service signaling data (such as PSI (programspecific information)/SI) can be separately gathered and sent by a datapipe. The Cell Mapper operates according to the dynamic informationproduced by the scheduler and the configuration of the frame structure.Details of the frame will be described later.

The frequency interleaver 7020 can randomly interleave data cellsreceived from the cell mapper 7010 to provide frequency diversity. Also,the frequency interleaver 7020 can operate on very OFDM symbol paircomprised of two sequential OFDM symbols using a differentinterleaving-seed order to get maximum interleaving gain in a singleframe.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 8 illustrates an OFDM generation block according to an embodimentof the present invention.

The OFDM generation block illustrated in FIG. 8 corresponds to anembodiment of the OFDM generation block 1030 described with reference toFIG. 1.

The OFDM generation block modulates the OFDM carriers by the cellsproduced by the Frame Building block, inserts the pilots, and producesthe time domain signal for transmission. Also, this block subsequentlyinserts guard intervals, and applies PAPR (Peak-to-Average Power Radio)reduction processing to produce the final RF signal.

Referring to FIG. 8, the frame building block can include a pilot andreserved tone insertion block 8000, a 2D-eSFN encoding block 8010, anIFFT (Inverse Fast Fourier Transform) block 8020, a PAPR reduction block8030, a guard interval insertion block 8040, a preamble insertion block8050, other system insertion block 8060 and a DAC block 8070.Description will be given of each block of the frame building block.

The pilot and reserved tone insertion block 8000 can insert pilots andthe reserved tone.

Various cells within the OFDM symbol are modulated with referenceinformation, known as pilots, which have transmitted values known apriori in the receiver. The information of pilot cells is made up ofscattered pilots, continual pilots, edge pilots, FSS (frame signalingsymbol) pilots and FES (frame edge symbol) pilots. Each pilot istransmitted at a particular boosted power level according to pilot typeand pilot pattern. The value of the pilot information is derived from areference sequence, which is a series of values, one for eachtransmitted carrier on any given symbol. The pilots can be used forframe synchronization, frequency synchronization, time synchronization,channel estimation, and transmission mode identification, and also canbe used to follow the phase noise.

Reference information, taken from the reference sequence, is transmittedin scattered pilot cells in every symbol except the preamble, FSS andFES of the frame. Continual pilots are inserted in every symbol of theframe. The number and location of continual pilots depends on both theFFT size and the scattered pilot pattern. The edge carriers are edgepilots in every symbol except for the preamble symbol. They are insertedin order to allow frequency interpolation up to the edge of thespectrum. FSS pilots are inserted in FSS(s) and FES pilots are insertedin FES. They are inserted in order to allow time interpolation up to theedge of the frame.

The system according to an embodiment of the present invention supportsthe SFN network, where distributed MISO scheme is optionally used tosupport very robust transmission mode. The 2D-eSFN is a distributed MISOscheme that uses multiple TX antennas, each of which is located in thedifferent transmitter site in the SFN network.

The 2D-eSFN encoding block 8010 can process a 2D-eSFN processing todistorts the phase of the signals transmitted from multipletransmitters, in order to create both time and frequency diversity inthe SFN configuration. Hence, burst errors due to low flat fading ordeep-fading for a long time can be mitigated.

The IFFT block 8020 can modulate the output from the 2D-eSFN encodingblock 8010 using OFDM modulation scheme. Any cell in the data symbolswhich has not been designated as a pilot (or as a reserved tone) carriesone of the data cells from the frequency interleaver. The cells aremapped to OFDM carriers.

The PAPR reduction block 8030 can perform a PAPR reduction on inputsignal using various PAPR reduction algorithm in the time domain.

The guard interval insertion block 8040 can insert guard intervals andthe preamble insertion block 8050 can insert preamble in front of thesignal. Details of a structure of the preamble will be described later.The other system insertion block 8060 can multiplex signals of aplurality of broadcast transmission/reception systems in the time domainsuch that data of two or more different broadcast transmission/receptionsystems providing broadcast services can be simultaneously transmittedin the same RF signal bandwidth. In this case, the two or more differentbroadcast transmission/reception systems refer to systems providingdifferent broadcast services. The different broadcast services may referto a terrestrial broadcast service, mobile broadcast service, etc. Datarelated to respective broadcast services can be transmitted throughdifferent frames.

The DAC block 8070 can convert an input digital signal into an analogsignal and output the analog signal. The signal output from the DACblock 7800 can be transmitted through multiple output antennas accordingto the physical layer profiles. A Tx antenna according to an embodimentof the present invention can have vertical or horizontal polarity.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions according to design.

FIG. 9 illustrates a structure of an apparatus for receiving broadcastsignals for future broadcast services according to an embodiment of thepresent invention.

The apparatus for receiving broadcast signals for future broadcastservices according to an embodiment of the present invention cancorrespond to the apparatus for transmitting broadcast signals forfuture broadcast services, described with reference to FIG. 1.

The apparatus for receiving broadcast signals for future broadcastservices according to an embodiment of the present invention can includea synchronization & demodulation module 9000, a frame parsing module9010, a demapping & decoding module 9020, an output processor 9030 and asignaling decoding module 9040. A description will be given of operationof each module of the apparatus for receiving broadcast signals.

The synchronization & demodulation module 9000 can receive input signalsthrough m Rx antennas, perform signal detection and synchronization withrespect to a system corresponding to the apparatus for receivingbroadcast signals and carry out demodulation corresponding to a reverseprocedure of the procedure performed by the apparatus for transmittingbroadcast signals.

The frame parsing module 9100 can parse input signal frames and extractdata through which a service selected by a user is transmitted. If theapparatus for transmitting broadcast signals performs interleaving, theframe parsing module 9100 can carry out deinterleaving corresponding toa reverse procedure of interleaving. In this case, the positions of asignal and data that need to be extracted can be obtained by decodingdata output from the signaling decoding module 9400 to restorescheduling information generated by the apparatus for transmittingbroadcast signals.

The demapping & decoding module 9200 can convert the input signals intobit domain data and then deinterleave the same as necessary. Thedemapping & decoding module 9200 can perform demapping for mappingapplied for transmission efficiency and correct an error generated on atransmission channel through decoding. In this case, the demapping &decoding module 9200 can obtain transmission parameters necessary fordemapping and decoding by decoding the data output from the signalingdecoding module 9400.

The output processor 9300 can perform reverse procedures of variouscompression/signal processing procedures which are applied by theapparatus for transmitting broadcast signals to improve transmissionefficiency. In this case, the output processor 9300 can acquirenecessary control information from data output from the signalingdecoding module 9400. The output of the output processor 8300corresponds to a signal input to the apparatus for transmittingbroadcast signals and may be MPEG-TSs, IP streams (v4 or v6) and genericstreams.

The signaling decoding module 9400 can obtain PLS information from thesignal demodulated by the synchronization & demodulation module 9000. Asdescribed above, the frame parsing module 9100, demapping & decodingmodule 9200 and output processor 9300 can execute functions thereofusing the data output from the signaling decoding module 9400.

FIG. 10 illustrates a frame structure according to an embodiment of thepresent invention.

FIG. 10 shows an example configuration of the frame types and FRUs in asuper-frame. (a) shows a super frame according to an embodiment of thepresent invention, (b) shows FRU (Frame Repetition Unit) according to anembodiment of the present invention, (c) shows frames of variable PHYprofiles in the FRU and (d) shows a structure of a frame.

A super-frame may be composed of eight FRUs. The FRU is a basicmultiplexing unit for TDM of the frames, and is repeated eight times ina super-frame.

Each frame in the FRU belongs to one of the PHY profiles, (base,handheld, advanced) or FEF. The maximum allowed number of the frames inthe FRU is four and a given PHY profile can appear any number of timesfrom zero times to four times in the FRU (e.g., base, base, handheld,advanced). PHY profile definitions can be extended using reserved valuesof the PHY_PROFILE in the preamble, if required.

The FEF part is inserted at the end of the FRU, if included. When theFEF is included in the FRU, the minimum number of FEFs is 8 in asuper-frame. It is not recommended that FEF parts be adjacent to eachother.

One frame is further divided into a number of OFDM symbols and apreamble. As shown in (d), the frame comprises a preamble, one or moreframe signaling symbols (FSS), normal data symbols and a frame edgesymbol (FES).

The preamble is a special symbol that enables fast Futurecast UTB systemsignal detection and provides a set of basic transmission parameters forefficient transmission and reception of the signal. The detaileddescription of the preamble will be will be described later.

The main purpose of the FSS(s) is to carry the PLS data. For fastsynchronization and channel estimation, and hence fast decoding of PLSdata, the FSS has more dense pilot pattern than the normal data symbol.The FES has exactly the same pilots as the FSS, which enablesfrequency-only interpolation within the FES and temporal interpolation,without extrapolation, for symbols immediately preceding the FES.

FIG. 11 illustrates a signaling hierarchy structure of the frameaccording to an embodiment of the present invention.

FIG. 11 illustrates the signaling hierarchy structure, which is splitinto three main parts: the preamble signaling data 11000, the PLS1 data11010 and the PLS2 data 11020. The purpose of the preamble, which iscarried by the preamble symbol in every frame, is to indicate thetransmission type and basic transmission parameters of that frame. ThePLS1 enables the receiver to access and decode the PLS2 data, whichcontains the parameters to access the DP of interest. The PLS2 iscarried in every frame and split into two main parts: PLS2-STAT data andPLS2-DYN data. The static and dynamic portion of PLS2 data is followedby padding, if necessary.

FIG. 12 illustrates preamble signaling data according to an embodimentof the present invention.

Preamble signaling data carries 21 bits of information that are neededto enable the receiver to access PLS data and trace DPs within the framestructure. Details of the preamble signaling data are as follows:

PHY_PROFILE: This 3-bit field indicates the PHY profile type of thecurrent frame. The mapping of different PHY profile types is given inbelow table 5.

TABLE 5 Value PHY profile 000 Base profile 001 Handheld profile 010Advanced profiled 011~110 Reserved 111 FEF

FFT_SIZE: This 2 bit field indicates the FFT size of the current framewithin a frame-group, as described in below table 6.

TABLE 6 Value FFT size 00  8K FFT 01 16K FFT 10 32K FFT 11 Reserved

GI_FRACTION: This 3 bit field indicates the guard interval fractionvalue in the current super-frame, as described in below table 7.

TABLE 7 Value GI_FRACTION 000 ⅕ 001 1/10 010 1/20 011 1/40 100 1/80 1011/160 110~111 Reserved

EAC_FLAG: This 1 bit field indicates whether the EAC is provided in thecurrent frame. If this field is set to ‘1’, emergency alert service(EAS) is provided in the current frame. If this field set to ‘0’, EAS isnot carried in the current frame. This field can be switched dynamicallywithin a super-frame.

PILOT_MODE: This 1-bit field indicates whether the pilot mode is mobilemode or fixed mode for the current frame in the current frame-group. Ifthis field is set to ‘0’, mobile pilot mode is used. If the field is setto ‘1’, the fixed pilot mode is used.

PAPR_FLAG: This 1-bit field indicates whether PAPR reduction is used forthe current frame in the current frame-group. If this field is set tovalue ‘1’, tone reservation is used for PAPR reduction. If this field isset to ‘0’, PAPR reduction is not used.

FRU_CONFIGURE: This 3-bit field indicates the PHY profile typeconfigurations of the frame repetition units (FRU) that are present inthe current super-frame. All profile types conveyed in the currentsuper-frame are identified in this field in all preambles in the currentsuper-frame. The 3-bit field has a different definition for eachprofile, as show in below table 8.

TABLE 8 Current Current Current PHY_PROFILE = PHY_PROFILE = CurrentPHY_PROFILE = ‘001’ ‘010’ PHY_PROFILE = ‘000’ (base) (handheld)(advanced) ‘111’ (FEF) FRU_CONFIGURE = Only base Only handheld Onlyadvanced Only FEF 000 profile present profile present profile presentpresent FRU_CONFIGURE = Handheld profile Base profile Base profile Baseprofile 1XX present present present present FRU_CONFIGURE = AdvancedAdvanced Handheld profile Handheld profile X1X profile present profilepresent present present FRU_CONFIGURE = FEF FEF FEF Advanced XX1 presentpresent present profile present

RESERVED: This 7-bit field is reserved for future use.

FIG. 13 illustrates PLS1 data according to an embodiment of the presentinvention.

PLS1 data provides basic transmission parameters including parametersrequired to enable the reception and decoding of the PLS2. As abovementioned, the PLS1 data remain unchanged for the entire duration of oneframe-group. The detailed definition of the signaling fields of the PLS1data are as follows:

PREAMBLE_DATA: This 20-bit field is a copy of the preamble signalingdata excluding the EAC_FLAG.

NUM_FRAME_FRU: This 2-bit field indicates the number of the frames perFRU.

PAYLOAD_TYPE: This 3-bit field indicates the format of the payload datacarried in the frame-group. PAYLOAD_TYPE is signaled as shown in table9.

TABLE 9 value Payload type 1XX TS stream is transmitted X1X IP stream istransmitted XX1 GS stream is transmitted

NUM_FSS: This 2-bit field indicates the number of FSS symbols in thecurrent frame.

SYSTEM_VERSION: This 8-bit field indicates the version of thetransmitted signal format. The SYSTEM_VERSION is divided into two 4-bitfields, which are a major version and a minor version.

Major version: The MSB four bits of SYSTEM_VERSION field indicate majorversion information. A change in the major version field indicates anon-backward-compatible change. The default value is ‘0000’. For theversion described in this standard, the value is set to ‘0000’.

Minor version: The LSB four bits of SYSTEM_VERSION field indicate minorversion information. A change in the minor version field isbackward-compatible.

CELL_ID: This is a 16-bit field which uniquely identifies a geographiccell in an ATSC network. An ATSC cell coverage area may consist of oneor more frequencies, depending on the number of frequencies used perFuturecast UTB system. If the value of the CELL_ID is not known orunspecified, this field is set to ‘0’.

NETWORK_ID: This is a 16-bit field which uniquely identifies the currentATSC network.

SYSTEM_ID: This 16-bit field uniquely identifies the Futurecast UTBsystem within the ATSC network. The Futurecast UTB system is theterrestrial broadcast system whose input is one or more input streams(TS, IP, GS) and whose output is an RF signal. The Futurecast UTB systemcarries one or more PHY profiles and FEF, if any. The same FuturecastUTB system may carry different input streams and use different RFfrequencies in different geographical areas, allowing local serviceinsertion. The frame structure and scheduling is controlled in one placeand is identical for all transmissions within a Futurecast UTB system.One or more Futurecast UTB systems may have the same SYSTEM_ID meaningthat they all have the same physical layer structure and configuration.

The following loop consists of FRU_PHY_PROFILE, FRU_FRAME_LENGTH,FRU_GI_FRACTION, and RESERVED which are used to indicate the FRUconfiguration and the length of each frame type. The loop size is fixedso that four PHY profiles (including a FEF) are signaled within the FRU.If NUM_FRAME_FRU is less than 4, the unused fields are filled withzeros.

FRU_PHY_PROFILE: This 3-bit field indicates the PHY profile type of the(i+1)^(th) (i is the loop index) frame of the associated FRU. This fielduses the same signaling format as shown in the table 8.

FRU_FRAME_LENGTH: This 2-bit field indicates the length of the(i+1)^(th) frame of the associated FRU. Using FRU_FRAME_LENGTH togetherwith FRU_GI_FRACTION, the exact value of the frame duration can beobtained.

FRU_GI_FRACTION: This 3-bit field indicates the guard interval fractionvalue of the (i+1)^(th) frame of the associated FRU. FRU_GI_FRACTION issignaled according to the table 7.

RESERVED: This 4-bit field is reserved for future use.

The following fields provide parameters for decoding the PLS2 data.

PLS2_FEC_TYPE: This 2-bit field indicates the FEC type used by the PLS2protection. The FEC type is signaled according to table 10. The detailsof the LDPC codes will be described later.

TABLE 10 Content PLS2 FEC type 00 4K-1/4 and 7K-3/10 LDPC codes 01~11Reserved

PLS2_MOD: This 3-bit field indicates the modulation type used by thePLS2. The modulation type is signaled according to table 11.

TABLE 11 Value PLS2_MODE 000 BPSK 001 QPSK 010 QAM-16 011 NUQ-64 100~111Reserved

PLS2_SIZE_CELL: This 15-bit field indicates C_(total) _(—) _(partial)_(—) _(block), the size (specified as the number of QAM cells) of thecollection of full coded blocks for PLS2 that is carried in the currentframe-group. This value is constant during the entire duration of thecurrent frame-group.

PLS2_STAT_SIZE_BIT: This 14-bit field indicates the size, in bits, ofthe PLS2-STAT for the current frame-group. This value is constant duringthe entire duration of the current frame-group.

PLS2_DYN_SIZE_BIT: This 14-bit field indicates the size, in bits, of thePLS2-DYN for the current frame-group. This value is constant during theentire duration of the current frame-group.

PLS2_REP_FLAG: This 1-bit flag indicates whether the PLS2 repetitionmode is used in the current frame-group. When this field is set to value‘1’, the PLS2 repetition mode is activated. When this field is set tovalue ‘0’, the PLS2 repetition mode is deactivated.

PLS2_REP_SIZE_CELL: This 15-bit field indicates C_(total) _(—)_(partial) _(—) _(block), the size (specified as the number of QAMcells) of the collection of partial coded blocks for PLS2 carried inevery frame of the current frame-group, when PLS2 repetition is used. Ifrepetition is not used, the value of this field is equal to 0. Thisvalue is constant during the entire duration of the current frame-group.

PLS2_NEXT_FEC_TYPE: This 2-bit field indicates the FEC type used forPLS2 that is carried in every frame of the next frame-group. The FECtype is signaled according to the table 10.

PLS2_NEXT_MOD: This 3-bit field indicates the modulation type used forPLS2 that is carried in every frame of the next frame-group. Themodulation type is signaled according to the table 11.

PLS2_NEXT_REP_FLAG: This 1-bit flag indicates whether the PLS2repetition mode is used in the next frame-group. When this field is setto value ‘1’, the PLS2 repetition mode is activated. When this field isset to value ‘0’, the PLS2 repetition mode is deactivated.

PLS2_NEXT_REP_SIZE_CELL: This 15-bit field indicates C_(total) _(—)_(full) _(—) _(block), The size (specified as the number of QAM cells)of the collection of full coded blocks for PLS2 that is carried in everyframe of the next frame-group, when PLS2 repetition is used. Ifrepetition is not used in the next frame-group, the value of this fieldis equal to 0. This value is constant during the entire duration of thecurrent frame-group.

PLS2_NEXT_REP_STAT_SIZE_BIT: This 14-bit field indicates the size, inbits, of the PLS2-STAT for the next frame-group. This value is constantin the current frame-group.

PLS2_NEXT_REP_DYN_SIZE_BIT: This 14-bit field indicates the size, inbits, of the PLS2-DYN for the next frame-group. This value is constantin the current frame-group.

PLS2_AP_MODE: This 2-bit field indicates whether additional parity isprovided for PLS2 in the current frame-group. This value is constantduring the entire duration of the current frame-group. The below table12 gives the values of this field. When this field is set to ‘00’,additional parity is not used for the PLS2 in the current frame-group.

TABLE 12 Value PLS2-AP mode 00 AP is not provided 01 AP1 mode 10~11Reserved

PLS2_AP_SIZE_CELL: This 15-bit field indicates the size (specified asthe number of QAM cells) of the additional parity bits of the PLS2. Thisvalue is constant during the entire duration of the current frame-group.

PLS2_NEXT_AP_MODE: This 2-bit field indicates whether additional parityis provided for PLS2 signaling in every frame of next frame-group. Thisvalue is constant during the entire duration of the current frame-group.The table 12 defines the values of this

FIELD

PLS2_NEXT_AP_SIZE_CELL: This 15-bit field indicates the size (specifiedas the number of QAM cells) of the additional parity bits of the PLS2 inevery frame of the next frame-group. This value is constant during theentire duration of the current frame-group.

RESERVED: This 32-bit field is reserved for future use.

CRC_(—)32: A 32-bit error detection code, which is applied to the entirePLS 1 signaling.

FIG. 14 illustrates PLS2 data according to an embodiment of the presentinvention.

FIG. 14 illustrates PLS2-STAT data of the PLS2 data. The PLS2-STAT dataare the same within a frame-group, while the PLS2-DYN data provideinformation that is specific for the current frame.

The details of fields of the PLS2-STAT data are as follows:

FIC_FLAG: This 1-bit field indicates whether the FIC is used in thecurrent frame-group. If this field is set to ‘1’, the FIC is provided inthe current frame. If this field set to ‘0’, the FIC is not carried inthe current frame. This value is constant during the entire duration ofthe current frame-group.

AUX_FLAG: This 1-bit field indicates whether the auxiliary stream(s) isused in the current frame-group. If this field is set to ‘1’, theauxiliary stream is provided in the current frame. If this field set to‘0’, the auxiliary stream is not carried in the current frame. Thisvalue is constant during the entire duration of current frame-group.

NUM_DP: This 6-bit field indicates the number of DPs carried within thecurrent frame. The value of this field ranges from 1 to 64, and thenumber of DPs is NUM_DP+1.

DP_ID: This 6-bit field identifies uniquely a DP within a PHY profile.

DP_TYPE: This 3-bit field indicates the type of the DP. This is signaledaccording to the below table 13.

TABLE 13 Value DP Type 000 DP Type 1 001 DP Type 2 010~111 reserved

DP_GROUP_ID: This 8-bit field identifies the DP group with which thecurrent DP is associated. This can be used by a receiver to access theDPs of the service components associated with a particular service,which will have the same DP_GROUP_ID.

BASE_DP_ID: This 6-bit field indicates the DP carrying service signalingdata (such as PSI/SI) used in the Management layer. The DP indicated byBASE_DP_ID may be either a normal DP carrying the service signaling dataalong with the service data or a dedicated DP carrying only the servicesignaling data

DP_FEC_TYPE: This 2-bit field indicates the FEC type used by theassociated DP. The FEC type is signaled according to the below table 14.

TABLE 14 Value FEC_TYPE 00 16K LDPC 01 64K LDPC 10~11 Reserved

DP_COD: This 4-bit field indicates the code rate used by the associatedDP. The code rate is signaled according to the below table 15.

TABLE 15 Value Code rate 0000 5/15 0001 6/15 0010 7/15 0011 8/15 01009/15 0101 10/15  0110 11/15  0111 12/15  1000 13/15  1001~1111 Reserved

DP_MOD: This 4-bit field indicates the modulation used by the associatedDP. The modulation is signaled according to the below table 16.

TABLE 16 Value Modulation 0000 QPSK 0001 QAM-16 0010 NUQ-64 0011 NUQ-2560100 NUQ-1024 0101 NUC-16 0110 NUC-64 0111 NUC-256 1000 NUC-10241001~1111 reserved

DP_SSD_FLAG: This 1-bit field indicates whether the SSD mode is used inthe associated DP. If this field is set to value ‘1’, SSD is used. Ifthis field is set to value ‘0’, SSD is not used.

The following field appears only if PHY_PROFILE is equal to ‘010’, whichindicates the advanced profile:

DP_MIMO: This 3-bit field indicates which type of MIMO encoding processis applied to the associated DP. The type of MIMO encoding process issignaled according to the table 17.

TABLE 17 Value MIMO encoding 000 FR-SM 001 FRFD-SM 010~111 reserved

DP_TI_TYPE: This 1-bit field indicates the type of time-interleaving. Avalue of ‘0’ indicates that one TI group corresponds to one frame andcontains one or more TI-blocks. A value of ‘1’ indicates that one TIgroup is carried in more than one frame and contains only one TI-block.

DP_TI_LENGTH: The use of this 2-bit field (the allowed values are only1, 2, 4, 8) is determined by the values set within the DP_TI_TYPE fieldas follows:

If the DP_TI_TYPE is set to the value ‘1’, this field indicates P_(I),the number of the frames to which each TI group is mapped, and there isone TI-block per TI group (N_(TI)=1). The allowed P_(I) values with2-bit field are defined in the below table 18.

If the DP_TI_TYPE is set to the value ‘0’, this field indicates thenumber of TI-blocks N_(TI) per TI group, and there is one TI group perframe (P_(I)=1). The allowed P_(I) values with 2-bit field are definedin the below table 18.

TABLE 18 2-bit field P_(I) N_(TI) 00 1 1 01 2 2 10 4 3 11 8 4

DP_FRAME_INTERVAL: This 2-bit field indicates the frame interval(I_(JUMP)) within the frame-group for the associated DP and the allowedvalues are 1, 2, 4, 8 (the corresponding 2-bit field is ‘00’, ‘01’,‘10’, or ‘11’, respectively). For DPs that do not appear every frame ofthe frame-group, the value of this field is equal to the intervalbetween successive frames. For example, if a DP appears on the frames 1,5, 9, 13, etc., this field is set to ‘4’. For DPs that appear in everyframe, this field is set to ‘1’.

DP_TI_BYPASS: This 1-bit field determines the availability of timeinterleaver. If time interleaving is not used for a DP, it is set to‘1’. Whereas if time interleaving is used it is set to ‘0’

DP_FIRST_FRAME_IDX: This 5-bit field indicates the index of the firstframe of the super-frame in which the current DP occurs. The value ofDP_FIRST_FRAME_IDX ranges from 0 to 31

DP_NUM_BLOCK_MAX: This 10-bit field indicates the maximum value ofDP_NUM_BLOCKS for this DP. The value of this field has the same range asDP_NUM_BLOCKS.

DP_PAYLOAD_TYPE: This 2-bit field indicates the type of the payload datacarried by the given DP. DP_PAYLOAD_TYPE is signaled according to thebelow table 19.

TABLE 19 Value Payload Type 00 TS. 01 IP 10 GS 11 reserved

DP_INBAND_MODE: This 2-bit field indicates whether the current DPcarries in-band signaling information. The in-band signaling type issignaled according to the below table 20.

TABLE 20 Value In-band mode 00 In-band signaling is not carried. 01INBAND-PLS is carried only 10 INBAND-ISSY is carried only 11 INBAND-PLSand INBAND-ISSY are carried

DP_PROTOCOL_TYPE: This 2-bit field indicates the protocol type of thepayload carried by the given DP. It is signaled according to the belowtable 21 when input payload types are selected.

TABLE 21 If DP_PAYLOAD_TYPE If DP_PAYLOAD_TYPE If DP_PAYLOAD_TYPE ValueIs TS Is IP Is GS 00 MPEG2-TS IPv4 (Note) 01 Reserved IPv6 Reserved 10Reserved Reserved Reserved 11 Reserved Reserved Reserved

DP_CRC_MODE: This 2-bit field indicates whether CRC encoding is used inthe Input Formatting block. The CRC mode is signaled according to thebelow table 22.

TABLE 22 Value CRC mode 00 Not used 01 CRC-8 10 CRC-16 11 CRC-32

DNP_MODE: This 2-bit field indicates the null-packet deletion mode usedby the associated DP when DP_PAYLOAD_TYPE is set to TS (‘00’). DNP_MODEis signaled according to the below table 23. If DP_PAYLOAD_TYPE is notTS (‘00’), DNP_MODE is set to the value ‘00’.

TABLE 23 Value Null-packet deletion mode 00 Not used 01 DNP-NORMAL 10DNP-OFFSET 11 reserved

ISSY_MODE: This 2-bit field indicates the ISSY mode used by theassociated DP when DP_PAYLOAD_TYPE is set to TS (‘00’). The ISSY_MODE issignaled according to the below table 24 If DP_PAYLOAD_TYPE is not TS(‘00’), ISSY_MODE is set to the value ‘00’.

TABLE 24 Value ISSY mode 00 Not used 01 ISSY-UP 10 ISSY-BBF 11 reserved

HC_MODE_TS: This 2-bit field indicates the TS header compression modeused by the associated DP when DP_PAYLOAD_TYPE is set to TS (‘00’). TheHC_MODE_TS is signaled according to the below table 25.

TABLE 25 Value Header compression mode 00 HC_MODE_TS 1 01 HC_MODE_TS 210 HC_MODE_TS 3 11 HC_MODE_TS 4

HC_MODE_IP: This 2-bit field indicates the IP header compression modewhen DP_PAYLOAD_TYPE is set to IP (‘01’). The HC_MODE_IP is signaledaccording to the below table 26.

TABLE 26 Value Header compression mode 00 No compression 01 HC_MODE_IP 110~11 reserved

PID: This 13-bit field indicates the PID number for TS headercompression when DP_PAYLOAD_TYPE is set to TS (‘00’) and HC_MODE_TS isset to ‘01’ or ‘10’.

RESERVED: This 8-bit field is reserved for future use.

The following field appears only if FIC_FLAG is equal to ‘1’:

FIC_VERSION: This 8-bit field indicates the version number of the FIC.

FIC_LENGTH_BYTE: This 13-bit field indicates the length, in bytes, ofthe FIC.

RESERVED: This 8-bit field is reserved for future use.

The following field appears only if AUX_FLAG is equal to ‘1’:

NUM_AUX: This 4-bit field indicates the number of auxiliary streams.Zero means no auxiliary streams are used.

AUX_CONFIG_RFU: This 8-bit field is reserved for future use.

AUX_STREAM_TYPE: This 4-bit is reserved for future use for indicatingthe type of the current auxiliary stream.

AUX_PRIVATE_CONFIG: This 28-bit field is reserved for future use forsignaling auxiliary streams.

FIG. 15 illustrates PLS2 data according to another embodiment of thepresent invention.

FIG. 15 illustrates PLS2-DYN data of the PLS2 data. The values of thePLS2-DYN data may change during the duration of one frame-group, whilethe size of fields remains constant.

The details of fields of the PLS2-DYN data are as follows:

FRAME_INDEX: This 5-bit field indicates the frame index of the currentframe within the super-frame. The index of the first frame of thesuper-frame is set to ‘0’.

PLS_CHANGE_COUNTER: This 4-bit field indicates the number ofsuper-frames ahead where the configuration will change. The nextsuper-frame with changes in the configuration is indicated by the valuesignaled within this field. If this field is set to the value ‘0000’, itmeans that no scheduled change is foreseen: e.g., value ‘1’ indicatesthat there is a change in the next super-frame.

FIC_CHANGE_COUNTER: This 4-bit field indicates the number ofsuper-frames ahead where the configuration (i.e., the contents of theFIC) will change. The next super-frame with changes in the configurationis indicated by the value signaled within this field. If this field isset to the value ‘0000’, it means that no scheduled change is foreseen:e.g. value ‘0001’ indicates that there is a change in the nextsuper-frame.

RESERVED: This 16-bit field is reserved for future use.

The following fields appear in the loop over NUM_DP, which describe theparameters associated with the DP carried in the current frame.

DP_ID: This 6-bit field indicates uniquely the DP within a PHY profile.

DP_START: This 15-bit (or 13-bit) field indicates the start position ofthe first of the DPs using the DPU addressing scheme. The DP_START fieldhas differing length according to the PHY profile and FFT size as shownin the below table 27.

TABLE 27 DP_START field size PHY profile 64K 16K Base 13 bit 15 bitHandheld — 13 bit Advanced 13 bit 15 bit

DP_NUM_BLOCK: This 10-bit field indicates the number of FEC blocks inthe current TI group for the current DP. The value of DP_NUM_BLOCKranges from 0 to 1023

RESERVED: This 8-bit field is reserved for future use.

The following fields indicate the FIC parameters associated with theEAC.

EAC_FLAG: This 1-bit field indicates the existence of the EAC in thecurrent frame. This bit is the same value as the EAC_FLAG in thepreamble.

EAS_WAKE_UP_VERSION_NUM: This 8-bit field indicates the version numberof a wake-up indication.

If the EAC_FLAG field is equal to ‘1’, the following 12 bits areallocated for EAC_LENGTH_BYTE field. If the EAC_FLAG field is equal to‘0’, the following 12 bits are allocated for EAC_COUNTER.

EAC_LENGTH_BYTE: This 12-bit field indicates the length, in byte, of theEAC.

EAC_COUNTER: This 12-bit field indicates the number of the frames beforethe frame where the EAC arrives.

The following field appears only if the AUX_FLAG field is equal to ‘1’:

AUX_PRIVATE_DYN: This 48-bit field is reserved for future use forsignaling auxiliary streams. The meaning of this field depends on thevalue of AUX_STREAM_TYPE in the configurable PLS2-STAT.

CRC_(—)32: A 32-bit error detection code, which is applied to the entirePLS2.

FIG. 16 illustrates a logical structure of a frame according to anembodiment of the present invention.

As above mentioned, the PLS, EAC, FIC, DPs, auxiliary streams and dummycells are mapped into the active carriers of the OFDM symbols in theframe. The PLS1 and PLS2 are first mapped into one or more FSS(s). Afterthat, EAC cells, if any, are mapped immediately following the PLS field,followed next by FIC cells, if any. The DPs are mapped next after thePLS or EAC, FIC, if any. Type 1 DPs follows first, and Type 2 DPs next.The details of a type of the DP will be described later. In some case,DPs may carry some special data for EAS or service signaling data. Theauxiliary stream or streams, if any, follow the DPs, which in turn arefollowed by dummy cells. Mapping them all together in the abovementioned order, i.e. PLS, EAC, FIC, DPs, auxiliary streams and dummydata cells exactly fill the cell capacity in the frame.

FIG. 17 illustrates PLS mapping according to an embodiment of thepresent invention. PLS cells are mapped to the active carriers ofFSS(s). Depending on the number of cells occupied by PLS, one or moresymbols are designated as FSS(s), and the number of FSS(s)N_(FSS) issignaled by NUM_FSS in PLS1. The FSS is a special symbol for carryingPLS cells. Since robustness and latency are critical issues in the PLS,the FSS(s) has higher density of pilots allowing fast synchronizationand frequency-only interpolation within the FSS.

PLS cells are mapped to active carriers of the N_(FSS) FSS(s) in atop-down manner as shown in an example in FIG. 17. The PLS1 cells aremapped first from the first cell of the first FSS in an increasing orderof the cell index. The PLS2 cells follow immediately after the last cellof the PLS1 and mapping continues downward until the last cell index ofthe first FSS. If the total number of required PLS cells exceeds thenumber of active carriers of one FSS, mapping proceeds to the next FSSand continues in exactly the same manner as the first FSS.

After PLS mapping is completed, DPs are carried next. If EAC, FIC orboth are present in the current frame, they are placed between PLS and“normal” DPs.

FIG. 18 illustrates EAC mapping according to an embodiment of thepresent invention.

EAC is a dedicated channel for carrying EAS messages and links to theDPs for EAS. EAS support is provided but EAC itself may or may not bepresent in every frame. EAC, if any, is mapped immediately after thePLS2 cells. EAC is not preceded by any of the FIC, DPs, auxiliarystreams or dummy cells other than the PLS cells. The procedure ofmapping the EAC cells is exactly the same as that of the PLS.

The EAC cells are mapped from the next cell of the PLS2 in increasingorder of the cell index as shown in the example in FIG. 18. Depending onthe EAS message size, EAC cells may occupy a few symbols, as shown inFIG. 18.

EAC cells follow immediately after the last cell of the PLS2, andmapping continues downward until the last cell index of the last FSS. Ifthe total number of required EAC cells exceeds the number of remainingactive carriers of the last FSS mapping proceeds to the next symbol andcontinues in exactly the same manner as FSS(s). The next symbol formapping in this case is the normal data symbol, which has more activecarriers than a FSS.

After EAC mapping is completed, the FIC is carried next, if any exists.If FIC is not transmitted (as signaled in the PLS2 field), DPs followimmediately after the last cell of the EAC.

FIG. 19 illustrates FIC mapping according to an embodiment of thepresent invention.

(a) shows an example mapping of FIC cell without EAC and (b) shows anexample mapping of FIC cell with EAC.

FIC is a dedicated channel for carrying cross-layer information toenable fast service acquisition and channel scanning. This informationprimarily includes channel binding information between DPs and theservices of each broadcaster. For fast scan, a receiver can decode FICand obtain information such as broadcaster ID, number of services, andBASE_DP_ID. For fast service acquisition, in addition to FIC, base DPcan be decoded using BASE_DP_ID. Other than the content it carries, abase DP is encoded and mapped to a frame in exactly the same way as anormal DP. Therefore, no additional description is required for a baseDP. The FIC data is generated and consumed in the Management Layer. Thecontent of FIC data is as described in the Management Layerspecification.

The FIC data is optional and the use of FIC is signaled by the FIC_FLAGparameter in the static part of the PLS2. If FIC is used, FIC_FLAG isset to ‘1’ and the signaling field for FIC is defined in the static partof PLS2. Signaled in this field are FIC_VERSION, and FIC_LENGTH_BYTE.FIC uses the same modulation, coding and time interleaving parameters asPLS2. FIC shares the same signaling parameters such as PLS2_MOD andPLS2_FEC. FIC data, if any, is mapped immediately after PLS2 or EAC ifany. FIC is not preceded by any normal DPs, auxiliary streams or dummycells. The method of mapping FIC cells is exactly the same as that ofEAC which is again the same as PLS.

Without EAC after PLS, FIC cells are mapped from the next cell of thePLS2 in an increasing order of the cell index as shown in an example in(a). Depending on the FIC data size, FIC cells may be mapped over a fewsymbols, as shown in (b).

FIC cells follow immediately after the last cell of the PLS2, andmapping continues downward until the last cell index of the last FSS. Ifthe total number of required FIC cells exceeds the number of remainingactive carriers of the last FSS, mapping proceeds to the next symbol andcontinues in exactly the same manner as FSS(s). The next symbol formapping in this case is the normal data symbol which has more activecarriers than a FSS.

If EAS messages are transmitted in the current frame, EAC precedes FIC,and FIC cells are mapped from the next cell of the EAC in an increasingorder of the cell index as shown in (b).

After FIC mapping is completed, one or more DPs are mapped, followed byauxiliary streams, if any, and dummy cells.

FIG. 20 illustrates a type of DP according to an embodiment of thepresent invention.

(a) shows type 1 DP and (b) shows type 2 DP.

After the preceding channels, i.e., PLS, EAC and FIC, are mapped, cellsof the DPs are mapped. A DP is categorized into one of two typesaccording to mapping method:

Type 1 DP: DP is mapped by TDM

Type 2 DP: DP is mapped by FDM

The type of DP is indicated by DP_TYPE field in the static part of PLS2.FIG. 20 illustrates the mapping orders of Type 1 DPs and Type 2 DPs.Type 1 DPs are first mapped in the increasing order of cell index, andthen after reaching the last cell index, the symbol index is increasedby one. Within the next symbol, the DP continues to be mapped in theincreasing order of cell index starting from p=0. With a number of DPsmapped together in one frame, each of the Type 1 DPs are grouped intime, similar to TDM multiplexing of DPs.

Type 2 DPs are first mapped in the increasing order of symbol index, andthen after reaching the last OFDM symbol of the frame, the cell indexincreases by one and the symbol index rolls back to the first availablesymbol and then increases from that symbol index. After mapping a numberof DPs together in one frame, each of the Type 2 DPs are grouped infrequency together, similar to FDM multiplexing of DPs.

Type 1 DPs and Type 2 DPs can coexist in a frame if needed with onerestriction; Type 1 DPs always precede Type 2 DPs. The total number ofOFDM cells carrying Type 1 and Type 2 DPs cannot exceed the total numberof OFDM cells available for transmission of DPs:

D _(DP1) +D _(DP2) ≦D _(DP)  [Expression 2]

where D_(DP1) is the number of OFDM cells occupied by Type 1 DPs,D_(DP2) is the number of cells occupied by Type 2 DPs. Since PLS, EAC,FIC are all mapped in the same way as Type 1 DP, they all follow “Type 1mapping rule”. Hence, overall, Type 1 mapping always precedes Type 2mapping.

FIG. 21 illustrates DP mapping according to an embodiment of the presentinvention.

(a) shows an addressing of OFDM cells for mapping type 1 DPs and (b)shows an an addressing of OFDM cells for mapping for type 2 DPs.

Addressing of OFDM cells for mapping Type 1 DPs (0, . . . , D_(DP1)−1)is defined for the active data cells of Type 1 DPs. The addressingscheme defines the order in which the cells from the TIs for each of theType 1 DPs are allocated to the active data cells. It is also used tosignal the locations of the DPs in the dynamic part of the PLS2.

Without EAC and FIC, address 0 refers to the cell immediately followingthe last cell carrying PLS in the last FSS. If EAC is transmitted andFIC is not in the corresponding frame, address 0 refers to the cellimmediately following the last cell carrying EAC. If FIC is transmittedin the corresponding frame, address 0 refers to the cell immediatelyfollowing the last cell carrying FIC. Address 0 for Type 1 DPs can becalculated considering two different cases as shown in (a). In theexample in (a), PLS, EAC and FIC are assumed to be all transmitted.Extension to the cases where either or both of EAC and FIC are omittedis straightforward. If there are remaining cells in the FSS aftermapping all the cells up to FIC as shown on the left side of (a).

Addressing of OFDM cells for mapping Type 2 DPs (0, . . . , D_(DP2)−1)is defined for the active data cells of Type 2 DPs. The addressingscheme defines the order in which the cells from the TIs for each of theType 2 DPs are allocated to the active data cells. It is also used tosignal the locations of the DPs in the dynamic part of the PLS2.

Three slightly different cases are possible as shown in (b). For thefirst case shown on the left side of (b), cells in the last FSS areavailable for Type 2 DP mapping. For the second case shown in themiddle, FIC occupies cells of a normal symbol, but the number of FICcells on that symbol is not larger than C_(FSS). The third case, shownon the right side in (b), is the same as the second case except that thenumber of FIC cells mapped on that symbol exceeds C_(FSS).

The extension to the case where Type 1 DP(s) precede Type 2 DP(s) isstraightforward since PLS, EAC and FIC follow the same “Type 1 mappingrule” as the Type 1 DP(s).

A data pipe unit (DPU) is a basic unit for allocating data cells to a DPin a frame.

A DPU is defined as a signaling unit for locating DPs in a frame. A CellMapper 7010 may map the cells produced by the TIs for each of the DPs. ATime interleaver 5050 outputs a series of TI-blocks and each TI-blockcomprises a variable number of XFECBLOCKs which is in turn composed of aset of cells. The number of cells in an XFECBLOCK, N_(cells), isdependent on the FECBLOCK size, N_(ldpc), and the number of transmittedbits per constellation symbol. A DPU is defined as the greatest commondivisor of all possible values of the number of cells in a XFECBLOCK,N_(cells), supported in a given PHY profile. The length of a DPU incells is defined as L_(DPU). Since each PHY profile supports differentcombinations of FECBLOCK size and a different number of bits perconstellation symbol, L_(DPU) is defined on a PHY profile basis.

FIG. 22 illustrates an FEC structure according to an embodiment of thepresent invention.

FIG. 22 illustrates an FEC structure according to an embodiment of thepresent invention before bit interleaving. As above mentioned, Data FECencoder may perform the FEC encoding on the input BBF to generateFECBLOCK procedure using outer coding (BCH), and inner coding (LDPC).The illustrated FEC structure corresponds to the FECBLOCK. Also, theFECBLOCK and the FEC structure have same value corresponding to a lengthof LDPC codeword.

The BCH encoding is applied to each BBF (K_(bch) bits), and then LDPCencoding is applied to BCH-encoded BBF (K_(ldpc) bits=N_(bch) bits) asillustrated in FIG. 22.

The value of N_(ldpc) is either 64800 bits (long FECBLOCK) or 16200 bits(short FECBLOCK).

The below table 28 and table 29 show FEC encoding parameters for a longFECBLOCK and a short FECBLOCK, respectively.

TABLE 28 BCH error LDPC correction Rate N_(ldpc) K_(ldpc) K_(bch)capability N_(bch)-K_(bch) 5/15 64800 21600 21408 12 192 6/15 2592025728 7/15 30240 30048 8/15 34560 34368 9/15 38880 38688 10/15  4320043008 11/15  47520 47328 12/15  51840 51648 13/15  56160 55968

TABLE 29 BCH error LDPC correction Rate N_(ldpc) K_(ldpc) K_(bch)capability N_(bch)-K_(bch) 5/15 16200 5400 5232 12 168 6/15 6480 63127/15 7560 7392 8/15 8640 8472 9/15 9720 9552 10/15  10800 10632 11/15 11880 11712 12/15  12960 12792 13/15  14040 13872

The details of operations of the BCH encoding and LDPC encoding are asfollows:

A 12-error correcting BCH code is used for outer encoding of the BBF.The BCH generator polynomial for short FECBLOCK and long FECBLOCK areobtained by multiplying together all polynomials.

LDPC code is used to encode the output of the outer BCH encoding. Togenerate a completed B_(ldpc) (FECBLOCK), P_(ldpc) (parity bits) isencoded systematically from each I_(ldpc), (BCH-encoded BBF), andappended to I_(ldpc). The completed B_(ldpc) (FECBLOCK) are expressed asfollow Expression.

B _(ldpc) =[I _(ldpc) P _(ldpc) ]=[i ₀ ,i ₁ , . . . , i _(K) _(ldpc) ⁻¹,p ₀ ,p ₁ , . . . p _(N) _(ldpc) _(-K) _(ldpc) ⁻¹]  [Expression 3]

The parameters for long FECBLOCK and short FECBLOCK are given in theabove table 28 and 29, respectively.

The detailed procedure to calculate N_(ldpc)−K_(ldpc) parity bits forlong FECBLOCK, is as follows:

1) Initialize the parity bits,

p ₀ =p ₁ =p ₂ = . . . =p _(N) _(ldpc) _(-K) _(ldpc) ⁻¹=0  [Expression 4]

2) Accumulate the first information bit—i₀, at parity bit addressesspecified in the first row of an addresses of parity check matrix. Thedetails of addresses of parity check matrix will be described later. Forexample, for rate 13/15:

p ₉₈₃ =p ₉₈₃ ⊕i ₀ p ₂₈₁₅ =p ₂₈₁₅ ⊕i ₀

p ₄₈₃₇ =p ₄₈₃₇ ⊕i ₀ p ₄₉₈₉ =p ₄₉₈₉ ⊕i ₀

p ₆₁₃₈ =p ₆₁₃₃ ⊕i ₀ p ₆₄₅₈ =p ₆₄₅₃ ⊕i ₀

p ₆₉₂₁ =p ₆₉₂₁ ⊕i ₀ p ₆₉₇₄ =p ₆₉₇₄ ⊕i ₀

p ₇₅₇₂ =p ₇₅₇₂ ⊕i ₀ p ₈₂₆₀ p ₈₂₆₀ ⊕i ₀

p ₈₄₉₆ p ₈₄₉₆ ⊕i ₀  [Expression 5]

3) For the next 359 information bits, i_(s), s=1, 2, . . . , 359accumulate i_(s) at parity bit addresses using following Expression.

{x+(s mod 360)×Q _(ldpc)} mod(N _(ldpc) −K _(ldpc))  [Expression 6]

where x denotes the address of the parity bit accumulator correspondingto the first bit i₀, and Q_(ldpc) is a code rate dependent constantspecified in the addresses of parity check matrix. Continuing with theexample, Q_(ldpcc)=24 for rate 13/15, so for information bit i₁, thefollowing operations are performed:

P ₁₀₀₇ =P ₁₀₀₇ ⊕i ₁ P ₂₈₃₉ =P ₂₈₃₉ ⊕i ₁

P ₄₈₆₁ =P ₄₈₆₁ ⊕i ₁ P ₅₀₁₃ =P ₅₀₁₃ ⊕i ₁

P ₆₁₆₂ =P ₆₁₆₂ ⊕i ₁ P ₆₄₈₇ =P ₆₄₈₂ ⊕i ₁

P ₆₉₄₅ =P ₆₉₄₅ ⊕i ₁ P ₆₉₉₈ =P ₆₉₉₈ ⊕i ₁

P ₇₅₉₆ =P ₇₅₉₆ ⊕i ₁ P ₈₂₈₄ =P ₈₂₈₄ ⊕i ₁

P ₈₅₂₀ P ₈₅₂₀ ⊕i ₁  [Expression 7]

4) For the 361^(st) information bit i₃₆₀, the addresses of the paritybit accumulators are given in the second row of the addresses of paritycheck matrix. In a similar manner the addresses of the parity bitaccumulators for the following 359 information bits i_(s), s=361, 362, .. . , 719 are obtained using the Expression 6, where x denotes theaddress of the parity bit accumulator corresponding to the informationbit i₃₆₀, i.e., the entries in the second row of the addresses of paritycheck matrix.

5) In a similar manner, for every group of 360 new information bits, anew row from addresses of parity check matrixes used to find theaddresses of the parity bit accumulators.

After all of the information bits are exhausted, the final parity bitsare obtained as follows:

6) Sequentially perform the following operations starting with i=1

p _(i) =p _(i) ⊕p _(i-1) , i=1,2, . . . , N _(ldpc) −K_(ldpc)−1  [Expression 8]

where final content of p_(i), i=0, 1, . . . N_(ldpc)−K_(ldpc)−1 is equalto the parity bit p_(i).

TABLE 30 Code Rate Q_(ldpc) 5/15 120 6/15 108 7/15 96 8/15 84 9/15 7210/15  60 11/15  48 12/15  36 13/15  24

This LDPC encoding procedure for a short FECBLOCK is in accordance witht LDPC encoding procedure for the long FECBLOCK, except replacing thetable 30 with table 31, and replacing the addresses of parity checkmatrix for the long FECBLOCK with the addresses of parity check matrixfor the short FECBLOCK.

TABLE 31 Code Rate Q_(ldpc) 5/15 30 6/15 27 7/15 24 8/15 21 9/15 1810/15  15 11/15  12 12/15  9 13/15  6

FIG. 23 illustrates a bit interleaving according to an embodiment of thepresent invention.

The outputs of the LDPC encoder are bit-interleaved, which consists ofparity interleaving followed by Quasi-Cyclic Block (QCB) interleavingand inner-group interleaving.

(a) shows Quasi-Cyclic Block (QCB) interleaving and (b) showsinner-group interleaving.

The FECBLOCK may be parity interleaved. At the output of the parityinterleaving, the LDPC codeword consists of 180 adjacent QC blocks in along FECBLOCK and 45 adjacent QC blocks in a short FECBLOCK. Each QCblock in either a long or short FECBLOCK consists of 360 bits. Theparity interleaved LDPC codeword is interleaved by QCB interleaving. Theunit of QCB interleaving is a QC block. The QC blocks at the output ofparity interleaving are permutated by QCB interleaving as illustrated inFIG. 23, where N_(cells)=64800/η_(mod) or 16200/η_(mod) according to theFECBLOCK length. The QCB interleaving pattern is unique to eachcombination of modulation type and LDPC code rate.

After QCB interleaving, inner-group interleaving is performed accordingto modulation type and order (η_(mod)) which is defined in the belowtable 32. The number of QC blocks for one inner-group, N_(QCB) _(—)_(IG), is also defined.

TABLE 32 Modulation type η_(mod) N_(QCB) _(—) _(IG) QAM-16 4 2 NUC-16 44 NUQ-64 6 3 NUC-64 6 6 NUQ-256 8 4 NUC-256 8 8 NUQ-1024 10 5 NUC-102410 10

The inner-group interleaving process is performed with N_(QCB) _(—)_(IG) QC blocks of the QCB interleaving output. Inner-group interleavinghas a process of writing and reading the bits of the inner-group using360 columns and N_(QCB) _(—) _(IG) rows. In the write operation, thebits from the QCB interleaving output are written row-wise. The readoperation is performed column-wise to read out m bits from each row,where m is equal to 1 for NUC and 2 for NUQ.

FIG. 24 illustrates a cell-word demultiplexing according to anembodiment of the present invention.

(a) shows a cell-word demultiplexing for 8 and 12 bpcu MIMO and (b)shows a cell-word demultiplexing for 10 bpcu MIMO.

Each cell word (c_(0,1), c_(1,1), . . . , c_(η mod-1,1)) of the bitinterleaving output is demultiplexed into (d_(1,0,m), d_(1,1,m) . . . ,d_(1, η mod-1,m)) and (d_(2,0,m), d_(2,1,m) . . . , d_(2, η mod-1,m)) asshown in (a), which describes the cell-word demultiplexing process forone XFECBLOCK.

For the 10 bpcu MIMO case using different types of NUQ for MIMOencoding, the Bit Interleaver for NUQ-1024 is re-used. Each cell word(c_(0,1), c_(1,1), . . . , C_(9,1)) of the Bit Interleaver output isdemultiplexed into (d_(1,0,m), d_(1,1,m), . . . , d_(1,3,m)) and(d_(2,0,m), d_(2,1,m), . . . , d_(2,5,m)), as shown in (b).

FIG. 25 illustrates a time interleaving according to an embodiment ofthe present invention.

(a) to (c) show examples of TI mode.

The time interleaver operates at the DP level. The parameters of timeinterleaving (TI) may be set differently for each DP.

The following parameters, which appear in part of the PLS2-STAT data,configure the TI:

DP_TI_TYPE (allowed values: 0 or 1): Represents the TI mode; ‘0’indicates the mode with multiple TI blocks (more than one TI block) perTI group. In this case, one TI group is directly mapped to one frame (nointer-frame interleaving). ‘1’ indicates the mode with only one TI blockper TI group. In this case, the TI block may be spread over more thanone frame (inter-frame interleaving).

DP_TI_LENGTH: If DP_TI_TYPE=‘0’, this parameter is the number of TIblocks N_(TI) per TI group. For DP_TI_TYPE=‘ 1’, this parameter is thenumber of frames P_(I) spread from one TI group.

DP_NUM_BLOCK_MAX (allowed values: 0 to 1023): Represents the maximumnumber of XFECBLOCKs per TI group.

DP_FRAME_INTERVAL (allowed values: 1, 2, 4, 8): Represents the number ofthe frames I_(JUMP) between two successive frames carrying the same DPof a given PHY profile.

DP_TI_BYPASS (allowed values: 0 or 1): If time interleaving is not usedfor a DP, this parameter is set to ‘1’. It is set to ‘0’ if timeinterleaving is used.

Additionally, the parameter DP_NUM_BLOCK from the PLS2-DYN data is usedto represent the number of XFECBLOCKs carried by one TI group of the DP.

When time interleaving is not used for a DP, the following TI group,time interleaving operation, and TI mode are not considered. However,the Delay Compensation block for the dynamic configuration informationfrom the scheduler will still be required. In each DP, the XFECBLOCKsreceived from the SSD/MIMO encoding are grouped into TI groups. That is,each TI group is a set of an integer number of XFECBLOCKs and willcontain a dynamically variable number of XFECBLOCKs. The number ofXFECBLOCKs in the TI group of index n is denoted by N_(xBLOCK) _(—)_(Group)(n) and is signaled as DP_NUM_BLOCK in the PLS2-DYN data. Notethat N_(xBLOCK) _(—) _(Group)(n) may vary from the minimum value of 0 tothe maximum value N_(xBLOCK) _(—) _(Group) _(—) _(MAX) (corresponding toDP_NUM_BLOCK_MAX) of which the largest value is 1023.

Each TI group is either mapped directly onto one frame or spread overP_(I) frames. Each TI group is also divided into more than one TIblocks(N_(TI)), where each TI block corresponds to one usage of timeinterleaver memory. The TI blocks within the TI group may containslightly different numbers of XFECBLOCKs. If the TI group is dividedinto multiple TI blocks, it is directly mapped to only one frame. Thereare three options for time interleaving (except the extra option ofskipping the time interleaving) as shown in the below table 33.

TABLE 33 Modes Descriptions Option-1 Each TI group contains one TI blockand is mapped directly to one frame as shown in (a). This option issignaled in the PLS2-STAT by DP_TI_TYPE = ‘0’ and DP_TI_LENGTH =‘1’(N_(TI) = 1). Option-2 Each TI group contains one TI block and ismapped to more than one frame. (b) shows an example, where one TI groupis mapped to two frames, i.e., DP_TI_LENGTH = ‘2’ (P_(I) = 2) andDP_FRAME_INTERVAL (I_(JUMP) = 2). This provides greater time diversityfor low data-rate services. This option is signaled in the PLS2-STAT byDP_TI_TYPE = ‘1’. Option-3 Each TI group is divided into multiple TIblocks and is mapped directly to one frame as shown in (c). Each TIblock may use full TI memory, so as to provide the maximum bit-rate fora DP. This option is signaled in the PLS2-STAT signaling by DP_TI_TYPE =‘0’ and DP_TI_LENGTH = N_(TI), while P_(I) = 1.

In each DP, the TI memory stores the input XFECBLOCKs (output XFECBLOCKsfrom the SSD/MIMO encoding block). Assume that input XFECBLOCKs aredefined as

(d_(n, s, 0, 0), d_(n, s, 0, 1), ⋯  , d_(n, s, 0, N_(cells) − 1), d_(n, s, 1, 0), ⋯  , d_(n, s, 1, N_(cells) − 1), ⋯  , d_(n, s, N_(xBLOCK _ TI)(n, s) − 1, 0), ⋯  , d_(n, s, N_(xBLOCK _ TI)(n, s) − 1, N_(cells) − 1)),

where d_(n,s,r,q) is the qth cell of the rth XFECBLOCK in the sth TIblock of the nth TI group and represents the outputs of SSD and MIMOencodings as follows.

$d_{n,s,r,q} = \left\{ \begin{matrix}{f_{n,s,r,q},} & {{the}\; {outputof}\mspace{11mu} {SSD\ldots}\; {encoding}} \\{g_{n,s,r,q},} & {{theoutputof}\mspace{11mu} {MIMOending}}\end{matrix} \right.$

In addition, assume that output XFECBLOCKs from the time interleaver aredefined as

(h_(n, s, 0), h_(n, s, 1), …  , h_(n, s, i), …  , h_(n, s, N_(xBLOCK_TI)(n, s) × N_(cells) − 1)),

where h_(n,s,i) is the ith output cell (for i=0, . . . , N_(xBLOCK) _(—)_(TI)(n,s)×N_(cells)−1) in the sth TI block of the nth TI group.

Typically, the time interleaver will also act as a buffer for DP dataprior to the process of frame building. This is achieved by means of twomemory banks for each DP. The first TI-block is written to the firstbank. The second TI-block is written to the second bank while the firstbank is being read from and so on.

The TI is a twisted row-column block interleaver. For the sth TI blockof the nth TI group, the number of rows N_(r) of a TI memory is equal tothe number of cells N_(cells), i.e., N_(r)=N_(cells) while the number ofcolumns N_(c) is equal to the number N_(xBLOCK) _(—) _(TI)(n,s).

FIG. 26 illustrates the basic operation of a twisted row-column blockinterleaver according to an embodiment of the present invention.

shows a writing operation in the time interleaver and (b) shows areading operation in the time interleaver The first XFECBLOCK is writtencolumn-wise into the first column of the TI memory, and the secondXFECBLOCK is written into the next column, and so on as shown in (a).Then, in the interleaving array, cells are read out diagonal-wise.During diagonal-wise reading from the first row (rightwards along therow beginning with the left-most column) to the last row, N_(r) cellsare read out as shown in (b). In detail, assuming z_(n,s,i)(i=0, . . . ,N_(r)N_(c)) as the TI memory cell position to be read sequentially, thereading process in such an interleaving array is performed bycalculating the row index the column index, and the associated twistingparameter T_(n,s,i) as follows expression.

$\begin{matrix}{{{GENERATE}\left( {R_{n,s,i},C_{n,s,i}} \right)} = \left\{ {{R_{n,s,i} = {{mod}\left( {i,N_{r}} \right)}},{T_{n,s,i} = {{mod}\left( {{S_{shift} \times R_{n,s,i}},N_{c}} \right)}},{C_{n,s,i} = {{mod}\left( {{T_{n,s,i} + \left\lfloor \frac{i}{N_{r}} \right\rfloor},N_{c}} \right)}}} \right\}} & \left\lbrack {{Expression}\mspace{14mu} 9} \right\rbrack\end{matrix}$

where S_(shift) is a common shift value for the diagonal-wise readingprocess regardless of N_(xBLOCK) _(—) _(TI)(n,s) and it is determined byN_(xBLOCK) _(—) _(TI) _(—) _(MAX) given in the PLS2-STAT as followsexpression.

$\begin{matrix}{{for}\left\{ {\begin{matrix}{{N_{{xBLOCK}\; \_ \; {TI}\; \_ \; {MAX}}^{\prime} = {N_{{xBLOCK}\; \_ \; {TI}\; \_ \; {MAX}} + 1}},} & {{{if}\mspace{14mu} N_{{xBLOCK}\; \_ \; {TI}\; \_ \; {MAX}}{mod}\; 2} = 0} \\{{N_{{xBLOCK}\; \_ \; {TI}\; \_ \; {MAX}}^{\prime} = N_{{xBLOCK}\; \_ \; {TI}\; \_ \; {MAX}}},} & {{{if}\mspace{14mu} N_{{xBLOCK}\; \_ \; {TI}\; \_ \; {MAX}}{mod}\; 2} = 1}\end{matrix},\mspace{79mu} {S_{shift} = \frac{N_{{xBLOCK}\; \_ \; {TI}\; \_ \; {MAX}}^{\prime} - 1}{2}}} \right.} & \left\lbrack {{Expression}\mspace{14mu} 10} \right\rbrack\end{matrix}$

As a result, the cell positions to be read are calculated by acoordinate as z_(n,s,i)=N_(r)C_(n,s,i)+R_(n,s,i).

FIG. 27 illustrates an operation of a twisted row-column blockinterleaver according to another embodiment of the present invention.

More specifically, FIG. 27 illustrates the interleaving array in the TImemory for each TI group, including virtual XFECBLOCKs when N_(xBLOCK)_(—) _(TI)(0,0)=3, N_(xBLOCK) _(—) _(TI)(1,0)=6, N_(xBLOCK) _(—)_(TI)(2,0)=5.

The variable number N_(xBLOCK) _(—) _(TI)(n,s)=N_(r) will be less thanor equal to N′_(xBLOCK) _(—) _(TI) _(—) _(MAX). Thus, in order toachieve a single-memory deinterleaving at the receiver side, regardlessof N_(xBLOCK) _(—) _(TI)(n,s) the interleaving array for use in atwisted row-column block interleaver is set to the size ofN_(r)×N_(c)=N_(cells)×N′_(xBLOCK) _(—) _(TI) _(—) _(MAX) by insertingthe virtual XFECBLOCKs into the TI memory and the reading process isaccomplished as follow expression.

[EXPRESSION 11] p = 0; for i = 0;i < N_(cells)N'_(xBLOCK)_TI_MAX; i =i + 1 {GENERATE (R_(n,s,i),C_(n,s,i)); V_(i) = N_(r)C_(n,s,j) +R_(n,s,j)  if V_(i) < N_(cells)N_(xBLOCK)_TI(n,s)  {  Z_(n,s,p) = V_(i);p = p + 1;  } }

The number of TI groups is set to 3. The option of time interleaver issignaled in the PLS2-STAT data by DP_TI_TYPE=‘0’, DP_FRAME_INTERVAL=‘1’,and DP_TI_LENGTH=‘1’, I_(JUMP)=1, and P₁=1. The number of XFECBLOCKs,each of which has N_(cells)=30 cells, per TI group is signaled in thePLS2-DYN data by N_(xBLOCK) _(—) _(TI)(0,0)=3, N_(xBLOCK) _(—)_(TI)(1,0)=6, and N_(xBLOCK) _(—) _(TI)(2,0)=5, respectively. Themaximum number of XFECBLOCK is signaled in the PLS2-STAT data byN_(xBLOCK) _(—) _(Group) _(—) _(MAX), which leads to └N_(xBLOCK) _(—)_(Group) _(—) _(MAX)/N_(TI)┘=N_(xBLOCK) _(—) _(TI) _(—) _(MAX)=6.

FIG. 28 illustrates a diagonal-wise reading pattern of a twistedrow-column block interleaver according to an embodiment of the presentinvention.

More specifically FIG. 28 shows a diagonal-wise reading pattern fromeach interleaving array with parameters of N′_(xBLOCK) _(—) _(TI) _(—)_(MAX)=7 and S_(shift)=(7−1)/2=3. Note that in the reading process shownas pseudocode above, if V_(i)≧N_(cells)N_(xBLOCK) _(—) _(TI)(n,s) thevalue of V_(i) is skipped and the next calculated value of V, is used.

FIG. 29 illustrates interlaved XFECBLOCKs from each interleaving arrayaccording to an embodiment of the present invention.

FIG. 29 illustrates the interleaved XFECBLOCKs from each interleavingarray with parameters of N′_(xBLOCK) _(—) _(TI) _(—) _(MAX)=7 andS_(shift)=3.

FIG. 30 illustrates a constellation mapper according to one embodimentof the present invention.

The constellation mapper according to one embodiment of the presentinvention performs the same operation as the constellation mapper of theBICM block described above.

The data received from the input formatting block described above may betransformed into a bit stream through FEC encoding. In the bit stream,multiple bits constitute a cell, and the cells may be mapped to one ofthe constellations in the complex plane by the constellation mapper.Herein, for N bits to be transmitted in one cell, 2̂N constellationpoints may be needed.

Herein, a constellation point may represent one constellation. Theconstellation point may be referred to as a constellation. 64-QAM, whichis a set of constellations, may be called a constellation set, aconstellation, and the like.

A constellation may be created using various methods. Depending on themethod used to arrange constellation points in a constellation, theprobability of errors occurring when the receiver decodes theconstellation into a bit stream may vary.

Types of constellations that the constellation mapper uses are as shownin FIGS. 30( a), 30(b) and 30(c). The constellations shown in thefigures are exemplary constellations of the respective types.Constellations of FIGS. 30( a) and 30(b) are all square QAMs. In thecase of FIG. 30( a), distances between constellation points arenon-uniform. In the case of FIG. 30( b), distances between constellationpoints are uniform. The constellation of FIG. 30( a) may correspond to anon-uniform QAM, and the constellation of FIG. 30( b) may correspond toa normal QAM. The constellation of FIG. 30( b) may be a special case ofFIG. 30( a).

The present invention proposes constellations as shown in FIG. 30( c)and a method for finding such constellations. According to the proposedmethod of the present invention, a lower probability of error, i.e., ahigher channel capacity, may be obtained at a given signal-to-noiseratio (SNR) than when the conventional method is used. Hereinafter, thepresent invention will be described in detail.

FIG. 31 illustrates a method for configuring an optimum constellationaccording to one embodiment of the present invention.

The present invention proposes a method of configuring an optimumconstellation based on Amplitude and Phase-Shift Keying (APSK). Toobtain a shaping gain, a constellation of a round shape needs to beconfigured. Accordingly, a modified APSK type constellation, i.e.,non-uniform APSK, may be utilized. With the non-uniform APSK, thedistance/angle between constellation points arranged on concentriccircles may not be uniform. Herein, the non-uniform APSK may be referredto as a non-uniform constellation (NUC).

To find positions of optimum constellation points,constellation-splitting and bit-allocation methods are proposed in thepresent invention.

Constellation splitting refers to creating constellations by dividingconstellation points. Starting with QPSK, each constellation point maybe split into two to create 8 constellation points. In a similar manner,16, 32, 64, . . . constellation points may be created. Bit allocationrefers to allocating 1 bit to each constellation every time the numberof constellation points doubles in each step.

Now, radius-angle splitting will be described below.

FIG. 31( a) shows one constellation point of QPSK. The labeling of thisconstellation point is 00. The constellation point of FIG. 31( a) may besplit in the radial direction to create two constellation points ofFIGS. 31( b) and 31(c). In addition, the constellation point of FIG. 31(a) may be split in the angular direction to create two constellationpoints of FIGS. 31( d) and 31(e).

Thereafter, the third bit may be allocated to each constellation. Asshown in the figures, the respective constellation points may beassigned bits in the form of xx0 or xx1. Herein, xx may denote thelabeling of a constellation point before the constellation point issplit, in which case the bits may be allocated as 000 or 001.

Similarly, splitting and bit allocation may also be implemented in theother quadrants of the complex plane as in the case of the firstquadrant. Before being split, the constellation points of FIG. 31( a)are symmetrical about the x-axis and the y-axis. Therefore, thepositions and labels of the constellation points in the other quadrantsmay be estimated through reflection. In this case, GRAY labeling for thethird bit allocated to the constellation points in the other quadrantsmay be maintained through reflection of the first quadrant.

FIG. 32 illustrates a method for configuring an optimum constellationaccording to another embodiment of the present invention.

Hereinafter, joint radius-angle splitting will be described.

The two methods of splitting (radial splitting and angular splitting)can be applied at the same time. In this case, four constellations of A,B, C and D may be created. 2 bits may be allocated to each of thecreated constellations such that GRAY labeling is implemented. As shownin FIG. 32, two bits may be allocated to allow each constellation tomaintain GRAY labeling in terms of radius and angle. Herein, GRAYlabeling may refer to allocating bits such that the difference betweenbits of neighboring constellations is 1 bit.

A and D, and B and C need not be disposed at the same radial position.Similarly, A and B, and C and D need not be disposed at the same angularposition. In the case of disposition at the same radial position orangular position, the number of parameters to be found later is reduced.Accordingly, the search time may be reduced, and the degree of freedomof the constellations may be correspondingly reduced as theconstellations are disposed at the same radial position or angularposition. That is, there may be a trade-off between the search time andthe capacity (performance) of the constellations.

In this embodiment, a case in which the constellations have the sameradius (OA=OD, OB=OC) may be considered to ensure short searching time.In addition, the size of a constellation, i.e. the number ofconstellation points, may be assumed to be 2̂m (m: even integer).However, this is simply illustrative, and the embodiments of the presentinvention are not limited thereto.

Similarly, labeling of constellations in the second, third and fourthquadrants is determined through reflection. As reflection isimplemented, GRAY labeling of each constellation may be maintained interms of radius and angle.

FIG. 33 illustrates creation of non-uniform constellations (NUCs)according to one embodiment of the present invention.

2̂m NUCs may be created using 2̂(m−2) NUCs. That is, the jointradius-angle splitting method described above may be used. Accordingly,16 NUCs may also be created using QPSK.

16 NUCs may have two rings. In each quadrant, two constellation pointsper quadrant may be present on each ring. Accordingly, all 16constellations may be included in the 16 NUCs. Herein, the rings mayrepresent concentric circles having the center thereof at the origin inthe complex plane.

In the equation shown in FIG. 33, r_(n) may denote the radius of eachring. Herein, n may denote the index of a ring and θ_(i,j) may representan angle by which constellation splitting is performed at the sameradius. Accordingly, the difference in angle between two constellationswhich are split along the same radius may be 2θ_(i,j). Herein, i maydenote the index of a ring, and j may denote a splitting index. Asdescribed above, the rings need not have the same distribution ofconstellations, and accordingly θ may have ring index i.

Accordingly, the coordinates of each constellation of 16 NUCs may beindicated by r₀, r₁, θ_(0,0), and θ_(1,0). Similarly, in the case of 64NUCs, the index n may range from 0 to 3, the index i may range from 0and 3, and the index j may range from 0 to 1. In the case of 256 NUCs,the index n may range from 0 to 7, the index i may range from 0 to 7,and the index j may range from 0 to 2. Each index has an integer value.

To generalize these cases, 2̂m NUCs may have 2̂(m/2−1) rings, and eachring may have k constellation points per quadrant. Herein, the value ofk may be m/2−1.

When r_(n) and θ_(i,j) that maximize the BICM capacity are found, aconstellation having the highest capacity may be obtained. It may beassumed that r₀ is set to 1. After r_(n) (n≠0) is found, it may not benecessary to separately determine r₀ since the average power can beassumed to be 1.

FIG. 34 shows an equation for bit allocation according to one embodimentof the present invention.

Hereinafter, a method of bit allocation will be described. Bits may needto be allocated such that the bits conform to the GRAY rule in terms ofradius and angle.

One constellation point of 2̂m constellations may transmit m bits. m bitsmay be named b₀b₁ . . . b_(m-1). In this case, 2 bits may be determineddepending on the quadrant in which the corresponding constellation pointis positioned. Half of the other m−2 bits may be determined by the ringindex, and the other half may be determined by the angular position onthe ring. For simplicity of description, it may be assumed in thisembodiment that b₀b₁ is determined by the quadrant, b₂b₄ . . . b_(m-2)is determined by the ring index, and b₃b₅ . . . b_(m-1) is determined bythe angle.

The coordinates of each constellation may be determined by the LOCequation shown in FIG. 34. For the constellations determined in thisway, the GRAY rule may be maintained between neighboring constellationpoints in terms of radius and angle.

Herein, the allocated bits may be exchanged with each other. Thisexchange may be performed with the GRAY rule maintained. In this case,even if the bits are exchanged, the overall BICM capacity may notchange. A function for such exchange may be referred to as ConvGRAY.

For example, when ConvGRAY is applied to 2 bits (m=2), one-to-oneexchange may be performed between {00, 01, 10, 11} and {00, 01, 11, 10}.Similarly, when ConvGRAY is applied to 3 bits (m=3), one-to-one exchangemay be performed between {000, 001, 010, 011, 100, 101, 110, 111} and{000, 001, 011, 010, 110, 111, 101, 100}.

In the case of 3 bits, six values are obtained after exchange. Thesevalues are defined as values 1, 2, 3, . . . , 6 for description. Thefirst bit of each of values 1, 2 and 3 is set to 0. The second and thirdbits of each of values 1, 2 and 3 are equal to the values obtainedthrough exchange in the case of 2 bits. The first bit of values 4, 5 and6 is set to 1. The second and third bits of each of values 4, 5 and 6are reverse arrangement of the values obtained through exchange in thecase of 2 bits.

When values obtained through exchange in the case of n−1 bits are found,the values obtained through exchange in the case of n bits can beestimated. When this method is applied to n bits, the equation shown inFIG. 34 may be obtained.

Inv_ConvGRAY may represent an inverse function of ConvGRAY. As describedabove, ConvGRAY function may determine b₂b₄ . . . b_(m-2) using a ringindex, or may determine b₃b₅ . . . b_(m-1) based on an angle. Thereverse function Inv_ConvGRAY may receive each bit value as an input andobtain a ring index and an angle. That is, the ring index may bedetermined using b₂b₄ . . . b_(m-2), and the angles may be determinedusing b₃b₅ . . . b_(m-1).

To measure the performance of the determined constellation, BICMcapacities of the determined constellation may be calculated andcompared. For the BICM capacities, Additive White Gaussian Noise (AWGN)and Individually Identical Distributed (IID) input may be assumed. AWGNmay represent a basic noise model that is basically used. IID mayrepresent that inputs are independently and equally/uniformlydistributed.

$\begin{matrix}{{B\; I\; C\; M\mspace{14mu} {{cap}.}} = {\sum\limits_{i}\left( {{\int_{Y}{{p\left( {{b_{i} = 0},y} \right)}\log_{2}\frac{p\left( {{b_{i} = 0},y} \right)}{{p\left( {b_{i} = 0} \right)}{p(y)}}{y}}} + {\int_{Y}{{p\left( {{b_{i} = 1},y} \right)}\log_{2}\frac{p\left( {{b_{i} = 1},y} \right)}{{p\left( {b_{i} = 1} \right)}{p(y)}}{y}}}} \right)}} & \left\lbrack {{Equation}\mspace{14mu} 12} \right\rbrack \\\begin{matrix}{\mspace{79mu} {{p\left( {{b_{i} = j},y} \right)} = {{p\left( {{yb_{i}} = j} \right)} \cdot {p\left( {b_{i} = j} \right)}}}} \\{= {\sum\limits_{M_{i}}{{p\left( {{yx} = M_{j}} \right)} \cdot \frac{1}{M}}}} \\{= {\sum\limits_{M_{i}}{\frac{1}{{\pi\sigma}^{2}}{^{\frac{- {{y - M_{j}}}^{2}}{\sigma^{2}}} \cdot \frac{1}{M}}}}}\end{matrix} & \left\lbrack {{Equation}\mspace{14mu} 13} \right\rbrack \\\begin{matrix}{\mspace{79mu} {\frac{p\left( {{b_{i} = j},y} \right)}{{p\left( {b_{i} = j} \right)}{p(y)}} = \frac{p\left( {{yb_{i}} = j} \right)}{p(y)}}} \\{= \frac{p\left( {{yb_{i}} = j} \right)}{\sum\limits_{j}{p\left( {{b_{i} = j},y} \right)}}} \\{= \frac{\sum\limits_{M_{i}}{\frac{1}{{\pi\sigma}^{2}}{^{\frac{- {{y - M_{j}}}^{2}}{\sigma^{2}}} \cdot \frac{2}{M}}}}{\sum\limits_{j}{\sum\limits_{M_{i}}{\frac{1}{{\pi\sigma}^{2}}{^{\frac{- {{y - M_{j}}}^{2}}{\sigma^{2}}} \cdot \frac{1}{M}}}}}}\end{matrix} & \left\lbrack {{Equation}\mspace{14mu} 14} \right\rbrack\end{matrix}$

The BICM capacity may be calculated using the equation above. Using thisequation, values of r and θ that maximize the BICM capacity may befound. Since the AWGN and IID inputs are assumed, it may be expectedthat y=x+n. Herein, n may denote AWGN. It may be assumed thatp(b_(i)=0), p(b_(i)=1)=1/2. That is, when x is a constellation, and M isa constellation size, it may be possible that p(x=M_(j))=1/M. Herein,M_(j) may be a constellation when b_(i)=j. As shown in FIG. 34, the BICMcapacity function may be represented as an integral of a Gaussianfunction.

Specifically, methods which can be used to find parameters r and θ mainclude algorithm A and algorithm B.

Hereinafter, algorithm A will be described.

First, Δ_(r) and Δ_(θ) may be selected. Thereafter, BICM capacities maybe calculated for all combinations of r_(i), and θ_(i,j) fromr_(i)ε{r_(i) _(—) init−Δ_(r), r_(i) _(—) init, r_(i) _(—) init+Δ_(r)}and θ_(i,j)ε{θ_(i,j) _(—) init−Δ_(θ), θ_(i,j) _(—) init, θ_(i,j) _(—)init+Δ_(θ)}. Herein, initial values r_(i) _(—) init and θ_(i,j) _(—)init may change to more optimum values for the algorithm.

For example, when the constellation size is 16, one r and two θ's aregiven, and therefore 3̂(1+2) BICM capacities may be calculated. Since r₀is assumed to be 1, there is one r.

After the calculated BICM capacities are compared, r_(i) _(—) init andθ_(i,j) _(—) init may be updated according to a parameter combinationhaving the highest BICM capacity. If the parameter combination havingthe highest BICM capacity is {r_(i) _(—) init, θ_(i,j) _(—) init},execution of the algorithm may be stopped. Otherwise, the parametercombination having the highest BICM capacity is taken as a new {r_(i)_(—) init, θ_(i,j) _(—) init} and the algorithm continues to beexecuted. As the algorithm is executed, the values of {r_(i) _(—) init,θ_(i,j) _(—) init} may continue to be updated.

Thereafter, the aforementioned algorithm may be executed by decreasingΔ_(r) and Δ_(θ) by half (binary search). That is, BICM capacities may becalculated and compared using Δ_(r) and Δ_(θ) decreased by half. Then,{r_(i) _(—) init, θ_(i,j) _(—) init} may be updated with a parametercombination having the highest capacity. In this example, BICMcapacities may be calculated with r_(i) satisfying r_(i)ε{r_(i) _(—)init−2Δ_(r), r_(i) _(—) init−Δ_(r), r_(i) _(—) init, r_(i) _(—)init+Δ_(r), r_(i) _(—) init+2Δ_(r)} and θ_(i,j) satisfyingθ_(i,j)ε{θ_(i,j) _(—) init−2Δ_(θ), θ_(i,j) _(—) init−Δ_(i,j), θ_(i,j)_(—) init, θ_(i,j) _(—) init+Δ_(θ), θ_(i,j) _(—) init+2Δ_(r)}.

Thereafter, execution of the algorithm may be stopped if the combinationhaving the highest capacity is {r_(i) _(—) init, θ_(i,j) _(—) init}, andotherwise, the algorithm may continue to be executed with the parametercombination having the capacity taken as a new {r_(i) _(—) init, θ_(i,j)_(—) init}.

By repeating the algorithm in this way, Δ_(r) and Δ_(θ) may besufficiently reduced. When it is determined that the BICM capacities aresaturated according to sufficient reduction of Δ_(r) and Δ_(θ),execution of the algorithm may be stopped.

In the case of algorithm A described above, if the number of parametersto be found is large, it may take a lot of time for the capacities to befinally saturated. In the case in which the number of parameters islarge, algorithm B, which is described below, may be used. Algorithm Bmay be independently used. If necessary, however, algorithm B may beused based on the result obtained from algorithm A.

Hereafter, algorithm B will be described.

First, an initial constellation may be configured. For example, theinitial constellation may be configured such that r_(n)=n+1 (n=0, 1, . .. ). 0 may be determined such that constellation points are distributeduniformly in the range between 0 and 2π, namely determined by equallydividing 2π. The initial constellation may converge on an optimumconstellation through this algorithm.

Indexes of two r parameters, i.e. r_(i) and r_(j), may be randomly anduniformly selected. For simplicity of illustration, it may be assumedthat i≦j. Since the overall average power is invariable, it may beexpected that |r_(i)|²+|r_(j)|̂²=C. Herein, C is a constant. Accordingly,the following condition may be established. 0≦|r_(i)|²≦C/2. Under thiscondition, all values of r_(i), and r_(j) may be checked for BICMcapacities. In this case, the binary search described above may be usedin checking. r_(i), and r_(j) may be updated with a parametercombination having the highest BICM capacity among the calculated BICMcapacities.

Herein, binary search may refer to a scheme in which the algorithmcontinues to be executed by updating parameter a with (a+b)/2 whenperformance with parameter a is lower than performance with parameter b.

Similarly, a ring index i may be randomly and uniformly selected.Thereby, θ_(i,j), which determines a constellation point positioned on aring corresponding to the ring index, may be optimized. Thisoptimization process may also employ the binary search. Herein, j mayhave values as j=0, 1, . . . , and θ_(i,n)≦θ_(i,m) may be assumed when nis less than or equal to m. Similarly, when θ_(i,n) is optimized usingthe binary search, optimum θ_(i,j) may be determined.

When it is determined that the BICM capacity has saturated, thealgorithm may be stopped. Otherwise, the algorithm may be repeated byreselecting indexes i and j of parameters r_(i), and r_(j).

In the case of algorithm B, it may be important to randomly anduniformly select parameters. Otherwise, it may take a long time for theBICM capacity to be saturated, or the BICM capacity may converge on alocal minima.

In the case in which algorithm A is executed first and then the resultfrom algorithm A is used as an initial value for algorithm B, the timetaken for the BICM capacity to be saturated may be significantlyshortened.

FIG. 35 illustrates created 16 NUCs and the bits allocated theretoaccording to one embodiment of the present invention.

Each constellation point may be represented as 4 bits (b₀b₁b₂b₃). b₀b₁may represent a label of QPSK prior to extension. b₂ may be a bitallocated when the point is split according to radius splitting. b₃ maybe a bit allocated when the point is split according to angle splitting.

The bits other than the first two bits b₀b₁ may be symmetric withrespect to the X-axis and Y-axis. As described above, b₀b₁ may determinethe quadrant in which the constellation point is placed, and each bitmay satisfy the GREY rule in terms of radius and angle.

The receiver may demap the bits from the constellation. This may be aprocess reverse to the process of mapping the bits to the constellationsdescribed above. LLR may be estimated through demapping. The estimatedLLR may be used in the form of a soft input in FEC decoding. Indemapping, the process of estimating LLR may be expressed in thefollowing equation.

$\begin{matrix}\begin{matrix}{\mspace{79mu} {{\Pr \left( {b_{i} = j} \right)} = {\sum\limits_{s_{k} \in \Lambda_{j}}{{\Pr \left( {s = s_{k}} \right)}\frac{\exp\left( \frac{{{r - {Hs}_{k}}}^{2}}{\sigma^{2}} \right)}{\sum\limits_{m = 0}^{M - 1}{\exp \left( \frac{{{r - {Hs}_{m}}}^{2}}{\sigma^{2}} \right)}}}}}} \\{= {\sum\limits_{s_{k} \in \Lambda_{j}}{C\; {\Pr \left( {s = s_{k}} \right)}{\exp\left( \frac{{{r - {Hs}_{k}}}^{2}}{\sigma^{2}} \right)}}}}\end{matrix} & \left\lbrack {{Equation}\mspace{14mu} 15} \right\rbrack \\\begin{matrix}{\mspace{79mu} {{L\; L\; {R\left( b_{i} \right)}} = {\log \left( \frac{\Pr \left( {b_{i} = 1} \right)}{\Pr \left( {b_{i} = 0} \right)} \right)}}} \\{= {\log \left( \frac{\sum\limits_{s_{k} \in \Lambda_{1}}{{\Pr \left( {s = s_{k}} \right)}{\exp\left( \frac{- {{r - {Hs}_{k}}}^{2}}{\sigma^{2}} \right)}}}{\sum\limits_{s_{k} \in \Lambda_{0}}{{\Pr \left( {s = s_{k}} \right)}{\exp \left( \frac{- {{r - {Hs}_{k}}}^{2}}{\sigma^{2}} \right)}}} \right)}} \\{= {\log\left( \frac{\sum\limits_{s_{k} \in \Lambda_{i}}{\exp\left( \frac{- {{r - {Hs}_{k}}}^{2}}{\sigma^{2}} \right)}}{\sum\limits_{s_{k} \in \Lambda_{0}}{\exp \left( \frac{- {{r - {Hs}_{k}}}^{2}}{\sigma^{2}} \right)}} \right)}}\end{matrix} & \left\lbrack {{Equation}\mspace{14mu} 16} \right\rbrack \\\begin{matrix}{{L\; L\; {R\left( b_{i} \right)}} \cong {\frac{{{r - {Hs}_{0}}}^{2}}{\sigma^{2}} - \frac{{{r - {Hs}_{1}}}^{2}}{\sigma^{2}}}} \\{= \frac{{H}^{2}\left( {{2{Re}\left\{ {t*s_{1}} \right\}} - {2{Re}\left\{ {t*s_{0}} \right\}} + {s_{0}}^{2} - {s_{1}}^{2}} \right)}{\sigma^{2}}}\end{matrix} & \left\lbrack {{Equation}\mspace{14mu} 17} \right\rbrack\end{matrix}$

Herein, C may be a constant, σ² may be a complex noise power, Λ_(j) maydenote a set of constellation points where the i-th bit is j. Herein, jmay be 0 or 1. In addition, Pr(s=s_(k)) may denote a priori probability.Here, it may be assumed that b_(i) satisfies equi-probability bit bybit. If iterative decoding is used, the assumption that b_(i) isequi-probable may not be valid, and a priori probability may need tochange according to external information from FEC. In addition, whenmax-log LLR is assumed, it may be possible that t=r/H. s1 may be aconstellation that is closest to t for which the i-th bit is 1, and s0may be a constellation that is closest to t for which the i-th bit is 0.

FIG. 36 shows the parameters of 16 NUCs created according to oneembodiment of the present invention.

The parameters may be determined using the method described above.Referring to FIGS. 36, r and 0 values providing an optimum capacity foreach SNR (dB) are listed. The optimum BICM capacity values calculatedfor the corresponding parameters are also listed. In the cases where r₀is not 1, the average power is normalized to 1.

FIG. 37 shows constellations for the respective SNRs based on theparameters of the 16 NUCs created according to one embodiment of thepresent invention.

In FIG. 37, the values of r and θ that provide optimum capacities forthe respective SNRs as determined according to the method describedabove are indicated by constellations in the complex plane.

FIG. 38 shows graphs for comparing the BICM capacities of 16 NUCscreated according to one embodiment of the present invention.

In FIG. 38, X-axis may represent SNR(dB), and Y-axis may represent BICMcapacity. The graphs may depict a difference (y value) between a Shannoncapacity and the capacity of the constellation at a given SNR (x value).Herein, the Shannon capacity may indicate the greatest BICM capacity inBICM theory. Accordingly, this may mean performance improves as the yvalue decreases.

Q16 may represent uniform 16-QAM, NuQ16 may represent non-uniform16-QAM, and NuA16 may represent NUC-16. As shown in FIG. 38, NUC-16according to the present invention may exhibit the best performance.

FIG. 39 shows some of 64 NUCs created according to one embodiment of thepresent invention and bits allocated thereto.

FIG. 40 shows the others of 64 NUCs created according to one embodimentof the present invention and bits allocated thereto.

The tables shown in FIGS. 39 and 40 list values of r and θ, indicated byconstellations in the complex plane, providing optimum capacities forthe respective SNRs determined according to the method described above.Herein, in cases where r₀ is not 1, the average power is normalized to1.

These two tables, which are separately shown in FIGS. 39 and 40 due tospace constraints, constitute one table.

FIG. 41 shows constellations for the respective SNRs based on theparameters of the 64 NUCs created according to one embodiment of thepresent invention.

In FIG. 41, the values of r and θ that provide optimum capacities forthe respective SNRs as determined according to the method describedabove are indicated by constellations in the complex plane.

FIG. 42 shows graphs for comparing the BICM capacities of 64 NUCscreated according to one embodiment of the present invention.

In FIG. 42, X-axis may represent SNR (dB), and the Y-axis may representBICM capacity. The graphs may depict a difference (y value) between aShannon capacity and the capacity of the constellation at a given SNR (xvalue). Herein, the Shannon capacity may indicate the greatest BICMcapacity in BICM theory. Accordingly, this may mean that performanceimproves as the y value decreases.

Q64 may represent uniform 64-QAM, NuQ64 may represent non-uniform64-QAM, and NuA64 may represent NUC-64. As shown in FIG. 42, NUC-64according to the present invention may exhibit the best performance.

FIG. 43 shows some of 256 NUCs created according to one embodiment ofthe present invention and bits allocated thereto.

FIG. 44 shows others of 256 NUCs created according to one embodiment ofthe present invention and bits allocated thereto.

FIG. 45 shows others of 256 NUCs created according to one embodiment ofthe present invention and bits allocated thereto.

FIG. 46 shows the others of 256 NUCs created according to one embodimentof the present invention and bits allocated thereto.

The tables shown in FIGS. 43 to 46 list values of r and θ, indicated byconstellations in the complex plane, providing the optimum capacitiesfor the respective SNRs determined according to the method describedabove. Herein, in cases where r₀ is not 1, the average power isnormalized to 1.

These four tables, which are separately shown in FIGS. 43 to 46 due tospace constraints, constitute one table.

FIG. 47 shows constellations for the respective SNRs based on theparameters of the 256 NUCs created according to one embodiment of thepresent invention.

In FIG. 47, the values of r and θ that provide optimum capacities forthe respective SNRs as determined according to the method describedabove are indicated by constellations in the complex plane.

FIG. 48 shows graphs for comparing the BICM capacities of 256 NUCscreated according to one embodiment of the present invention.

In FIG. 48, X-axis may represent SNR (dB), and Y-axis may represent BICMcapacity. The graphs may depict a difference (y value) between a Shannoncapacity and the capacity of the constellation at a given SNR (x value).Herein, the Shannon capacity may indicate the greatest BICM capacity inBICM theory. Accordingly, this may mean that performance improves as they value decreases.

Q256 may represent uniform 256-QAM, NuQ256 may represent non-uniform256-QAM, and NuA256 may represent NUC-256. As shown in FIG. 48, NUC-256according to the present invention may exhibit the best performance.

FIG. 49 shows some of 1024 NUCs created according to one embodiment ofthe present invention and bits allocated thereto.

FIG. 50 shows others of 1024 NUCs created according to one embodiment ofthe present invention and bits allocated thereto.

FIG. 51 shows others of 1024 NUCs created according to one embodiment ofthe present invention and bits allocated thereto.

FIG. 52 shows others of 1024 NUCs created according to one embodiment ofthe present invention and bits allocated thereto.

FIG. 53 shows others of 1024 NUCs created according to one embodiment ofthe present invention and bits allocated thereto.

FIG. 54 shows others of 1024 NUCs created according to one embodiment ofthe present invention and bits allocated thereto.

FIG. 55 shows others of 1024 NUCs created according to one embodiment ofthe present invention and bits allocated thereto.

FIG. 56 shows others of 1024 NUCs created according to one embodiment ofthe present invention and bits allocated thereto.

FIG. 57 shows others of 1024 NUCs created according to one embodiment ofthe present invention and bits allocated thereto.

FIG. 58 shows the others of 1024 NUCs created according to oneembodiment of the present invention and bits allocated thereto.

The tables shown in FIGS. 49 to 58 list values of r and θ, indicated byconstellations in the complex plane, providing the optimum capacitiesfor the respective SNRs determined according to the method describedabove. Herein, in cases where r₀ is not 1, the average power isnormalized to 1.

These ten tables, which are separately shown in FIGS. 43 to 46 due tospace constraints, constitute one table.

FIG. 59 shows constellations for the respective SNRs based on theparameters of the 1024 NUCs created according to one embodiment of thepresent invention.

In FIG. 59, the values of r and θ that provide optimum capacities forthe respective SNRs as determined according to the method describedabove are indicated by constellations in the complex plane.

FIG. 60 shows graphs for comparing the BICM capacities of 1024 NUCscreated according to one embodiment of the present invention.

In FIG. 60, the X-axis may represent SNR (dB), and the Y-axis mayrepresent BICM capacity. The graphs may show a different (y value)between a Shannon capacity and the capacity of the constellation at agiven SNR (x value). Herein, the Shannon capacity may indicate thegreatest BICM capacity in BICM theory. Accordingly, this may mean thatperformance improves as the y value decreases.

Q1024 may represent uniform 1024-QAM, NuQ1024 may represent non-uniform1024-QAM, and NuA1024 may represent NUC-1024. As shown in FIG. 60,NUC-1024 according to the present invention may exhibit the bestperformance.

Observe that QAM-16 and NUQs are square shaped, while NUCs havearbitrary shape. When each constellation is rotated by any multiple of90 degrees, the rotated constellation exactly overlaps with its originalone. This “rotation-sense” symmetric property makes the capacities andthe average powers of the real and imaginary components equal to eachother.

FIG. 61 shows a constellation of 16 NUCs for 5/15 code rate andcoordinates of the respective constellations of 16 NUCs for 5/15 coderate according to an embodiment of the present invention.

The left side of FIG. 61 shows the constellation of 16 NUCs for 5/15code rate and the right side of FIG. 61 shows a table including thecoordinates of the respective constellations of 16 NUCs for 5/15 coderate. The coordinates represent the constellation points to which therespective bit values are allocated.

FIG. 62 shows a constellation of 16 NUCs for 6/15 code rate andcoordinates of the respective constellations of 16 NUCs for 6/15 coderate according to an embodiment of the present invention.

The left side of FIG. 62 shows the constellation of 16 NUCs for 6/15code rate and the right side of FIG. 62 shows a table including thecoordinates of the respective constellations of 16 NUCs for 6/15 coderate. The coordinates represent the constellation points to which therespective bit values are allocated.

FIG. 63 shows a constellation of 16 NUCs for 7/15 code rate andcoordinates of the respective constellations of 16 NUCs for 7/15 coderate according to an embodiment of the present invention.

The left side of FIG. 63 shows the constellation of 16 NUCs for 7/15code rate and the right side of FIG. 63 shows a table including thecoordinates of the respective constellations of 16 NUCs for 7/15 coderate. The coordinates represent the constellation points to which therespective bit values are allocated.

FIG. 64 shows a constellation of 16 NUCs for 8/15 code rate andcoordinates of the respective constellations of 16 NUCs for 8/15 coderate according to an embodiment of the present invention.

The left side of FIG. 64 shows the constellation of 16 NUCs for 8/15code rate and the right side of FIG. 64 shows a table including thecoordinates of the respective constellations of 16 NUCs for 8/15 coderate. The coordinates represent the constellation points to which therespective bit values are allocated.

FIG. 65 shows a constellation of 16 NUCs for 9/15 code rate andcoordinates of the respective constellations of 16 NUCs for 9/15 coderate according to an embodiment of the present invention.

The left side of FIG. 65 shows the constellation of 16 NUCs for 9/15code rate and the right side of FIG. 65 shows a table including thecoordinates of the respective constellations of 16 NUCs for 9/15 coderate. The coordinates represent the constellation points to which therespective bit values are allocated.

FIG. 66 shows a constellation of 16 NUCs for 10/15 code rate andcoordinates of the respective constellations of 16 NUCs for 10/15 coderate according to an embodiment of the present invention.

The left side of FIG. 66 shows the constellation of 16 NUCs for 10/15code rate and the right side of FIG. 66 shows a table including thecoordinates of the respective constellations of 16 NUCs for 10/15 coderate. The coordinates represent the constellation points to which therespective bit values are allocated.

FIG. 67 describes a process of mapping IQ-balanced/IQ-symmetricnon-uniform constellations according to one embodiment of the presentinvention.

As another constellation creation method for obtaining the optimum BICMcapacities, IQ-balanced/IQ-symmetric non-uniform constellation mappingis proposed.

To find constellation points that maximize the BICM capacity, someassumptions and restraints are needed. Hereinafter, some restraints willbe described.

Restraint 1. All constellation points are generated with the sameprobability. The probabilities of the constellation points may be equalto each other.

Restraint 2. Constellation points do not have a bias. That is, theaverage of all the constellation points may be 0. In addition, whenRestraint 1 is applied, the total sum of the constellation points may be0.

Restraint 3. The average power of the constellations is a constant. Thatis, the average power may be invariably set to a constant P.

Restraint 4-1. To implement IQ-balanced mapping, the BICM capacity onthe I-axis needs to be equal to the BICM capacity on the Q-axis. Forexample, if a constellation rotated by a multiple of 90 degrees such as90, 180 and 270 degrees coincides with the original constellation, thisconstellation may be viewed as being IQ-balanced. That is, if aconstellation point rotated by a multiple of 90 degrees overlaps one ofconstellation points from an original constellation set, theconstellation may be viewed as being IQ-balanced. Hereinafter, a case inwhich a constellation rotated by a multiple of 90 degrees coincides withthe original constellation will be considered as an IQ-balanced mappingscheme.

Restraint 4-2. To implement IQ-symmetric mapping, the BICM capacity inthe I-axis should not be equal to the BICM capacity in the Q-axis. Toimplement IQ-symmetric mapping, constellations should be symmetric withrespect to I-axis and Q-axis. For example, when s_(i) is a constellationpoint of a constellation, conj(s_(i)), −conj(s_(i)), and −s_(i) may alsoneed to be constellation points of the constellation.

Restraint 4-1 and Restraint 4-2 may not be simultaneously met. Toimplement IQ-balanced mapping, Restraint 4-1 may need to be met. Toimplement IQ-symmetric mapping, Restraint 4-2 may need to be met. Toimplement both IQ-balanced mapping and IQ-symmetric mapping, these tworestraints need to be met.

Hereinafter, a description will be given of a method of creatingnon-uniformly distributed constellation points according toIQ-balanced/IQ-symmetric non-uniform constellation mapping.

According to one embodiment, constellation points may be moved in thetwo-dimensional complex plane to find a constellation providing theoptimum capacity. By moving the constellation points, a constellationproviding the optimum BICM capacity may be found.

However, moving only one constellation point may not satisfy Restraint 1and/or Restraint 2 described above. Accordingly, to satisfy therestraints by moving this constellation point, another constellationpoint may also need to be moved. In this embodiment, the i-th and j-thconstellation points are moved.

It is assumed that the constellation prior to moving the constellationpoints is subject to IQ-balanced mapping. To maintain IQ-balancing, notonly the i-th and j-th constellation point pairs but also three otherconstellation point pairs corresponding thereto may need to be moved.The three corresponding constellation point pairs may refer toconstellation points obtained by rotating the i-th and j-thconstellation points by 90, 180 and 270 degrees. That is, 8constellation points may need to be moved together.

The i-th and j-th constellation points to be moved may be defined asS_(0,i) and S_(0,j), and the corresponding constellation points to bemoved may be defined as s_(k,i) and s_(k,j). Herein, k=1, 2, 3, and thepairs may respectively represent rotation of S_(0,i) and s_(0,j) by 90,180 and 270 degrees.

For constellation point s_(0,i), s_(0,j), a and b may be defined asEquation (1) and (2) shown in FIG. 67. Herein, Equation (1) and (2) mayrespectively mean that Restraint 1 and Restraint 2 are met while theconstellations are moved. That is, a and b may be constants. Inaddition, when S_(0,i) and a are expressed as Equation (3) shown in FIG.91, Equation (4) may be obtained. Then, Equation (5) may be derived fromthese equations. It can be seen from Equation (5) that movement of twoconstellation points can be controlled using one variable θ. Since theother constellation point pairs can be described with s_(0,i), ands_(0,j) as in Equation (6), all the constellation points may becontrolled by one variable.

Since movement is implemented with IQ-balancing maintained, thecharacteristic of IQ-balancing may be maintained even after movement. Inthis way, a constellation having the optimum capacity may be found withIQ-balancing maintained. When movement is implemented to find theconstellation, θ may be split into several parts to calculate the BICMcapacity for each split θ to find θ that maximizes the BICM capacity.Using this process, all four sets of s_(i) and s_(j) may be updated.

Hereinafter, specific steps of constructing a constellation havingnon-uniformly distributed constellation points will be described. Eachstep may be omitted or replaced with another step, or the sequentialorder of these steps may change. These steps are intended to describethe spirit of the present invention, not to limit the present invention.

First, an initial constellation may be configured. This initialconstellation may be an IQ-balanced or IQ-symmetric constellation. Forexample, the initial constellation may be a uniform QAM, a non-uniformQAM, or a non-uniform constellation (NUC). Herein, the NUC may be theNUC described above.

Two constellation points (s_(0,i), s_(0,j)) of the initial constellationmay be randomly and uniformly selected. The two constellation pointsshould be different from each other. The constellation points may beselected in the first quadrant.

Once the two constellation points are selected, the other constellationpoints in the second, third and fourth quadrants may also be naturallyselected. Accordingly, all eight constellation points may be selected.If the initial constellation is an IQ-balanced constellation, each ofthe selected constellations may be represented as e^(jkπ/2). S_(0,i).Here, k=0, 1, 2, 3, and i may be replaced with j. If the initialconstellation is an IQ-symmetric constellation, each of the selectedconstellations may be represented as conj(s_(0,i)), −conj(s_(0,i)) and−s_(0,i). i may be replaced with j. As described above, if the initialconstellation is an IQ-balanced or IQ-symmetric constellation, theaverage of the constellation may be 0.

Thereafter, |s_(0,i)|²+|s_(0,j)|² and the BICM capacity may becalculated. The constellation points may be respectively moved such thatthe BICM capacity is maximized. There may be two methods for finding theoptimum constellation position.

One method is to utilize Δ_(i). s_(0,i) may be moved by ±Δ_(i)vertically or horizontally. Accordingly, s_(0,j) may also need to bemoved by ±Δ_(j) vertically or horizontally. Herein, Δ_(j) and Δ_(i) maybe determined using |s_(0,i)|²+|s_(0,j)|². Accordingly, there may befour cases of movement such as (+Δ_(i), +Δ_(j)), (+Δ_(i), −Δ_(j)),(−Δ_(i), +Δ_(j)), (−Δ_(i), −Δ_(j)). This method may be used forIQ-symmetric non-uniform constellation mapping.

The other method is to utilize θ. As described, movement ofconstellations may be controlled by θ Accordingly, by changing θ by aproperly small angle each time, a constellation having the optimumcapacity may be found. According to an embodiment, the properly smallangle may be 1 degree in an embodiment. In addition, the angle may rangefrom 0 degree to 360 degrees. In addition, this range of angle may covers_(0,i)-a/2 and s_(0,j)-a/2. This is intended to set the optimumcapacity within the search range. That is, this is intended to preventthe capacity from being reduced in the search process. This method maybe used for IQ-balanced non-uniform constellation mapping.

According to the two methods described above, the BICM capacity may becalculated at constellation positions to which the constellations arerespectively moved. If the BICM capacity for the moved constellation isgreater than the BICM capacity calculated at first, s_(0,i) and s_(0,j)may be updated with this constellation.

Thereafter, constellations may continue to be searched by reducing Δ_(i)and θ. When these two parameters are sufficiently reduced, two otherconstellation points of the initial constellation may be selected anew.Then, the optimum position may be found for the newly selectedconstellation points through the process described above.

When all the BICM capacities are saturated, the algorithm may be stoppedand the final constellation set may be obtained. Herein, saturation ofthe capacities may refer to a case in which great increase in the BICMcapacity does not occur in the above algorithm. Saturation of the BICMcapacity may be checked every time s_(i) and s_(j) change, or may bechecked when all M constellation points are checked.

According to one embodiment, a constellation exhibiting the bestperformance may be selected after the algorithm is executed for all theseed constellations described above. The seed constellations, namely theinitial constellations, may include a uniform QAM, a non-uniform QAM,and a non-uniform constellation (NUC). For example, NUC-64 at the SNR of10 dB may be obtained by executing the algorithm for the QAM, NUQ andNUC. According to one embodiment, a constellation obtained through theaforementioned algorithm at 9.5 dB or 10.5 dB may be taken as a seedconstellation for the algorithm to be executed.

FIG. 68 shows constellations of 64 NUCs at the SNR of 18 dB using themethod of IQ-balanced non-uniform constellation mapping according to oneembodiment of the present invention.

In this embodiment, uniform-64-QAM having the average power of 1 istaken as a seed constellation, and a desired constellation is foundthrough θ. In addition, the angular increment is set to 1 degree,saturation of the capacity is checked after all M constellation pointsare updated with s_(i) and s_(j) once. Saturation checking may beperformed by checking whether the BICM capacity increases by 1.0e-5 ormore. This constellation may remain in the IQ-balanced state and satisfythe n*pi/2-symmetric condition.

FIG. 69 shows a constellation and the coordinates of the constellationsof 16 NUCs for 11/15 code rate based on the IQ-balanced non-uniformconstellation mapping method according to an embodiment of the presentinvention. The left side of FIG. 69 shows the constellation of 16 NUCsfor 11/15 code rate and the right side of FIG. 69 shows a tableincluding the coordinates of the respective constellations. Thecoordinates represent the constellation points to which the respectivebit values are allocated.

FIG. 70 shows a constellation and the coordinates of the constellationsof 16 NUCs for 12/15 code rate based on the IQ-balanced non-uniformconstellation mapping method according to an embodiment of the presentinvention. The left side of FIG. 70 shows the constellation of 16 NUCsfor 12/15 code rate and the right side of FIG. 70 shows a tableincluding the coordinates of the respective constellations. Thecoordinates represent the constellation points to which the respectivebit values are allocated.

FIG. 71 shows a constellation and the coordinates of the constellationsof 16 NUCs for 13/15 code rate based on the IQ-balanced non-uniformconstellation mapping method according to an embodiment of the presentinvention. The left side of FIG. 71 shows the constellation of 16 NUCsfor 13/15 code rate and the right side of FIG. 71 shows a tableincluding the coordinates of the respective constellations. Thecoordinates represent the constellation points to which the respectivebit values are allocated.

A description is now given of Future cast constellations according to anembodiment of the present invention.

The constellation mapper 5030 according to an embodiment of the presentinvention may be designed to maximize BICM capacity in Additive WhiteGaussian Noise (AWGN) and Rayleigh channels. This can be achievedthrough BICM capacity analysis and BER simulation with LDPC encoding andBit interleaving. In particular, the constellation mapper 5030 accordingto an embodiment of the present invention may operate to achievedifferent reliabilities per bits.

The constellation mapper 5030 according to an embodiment of the presentinvention may provide 1-dimensional constellations and 2-dimensionalconstellations.

A description is now given of 1-dimensional constellations and2-dimensional constellations according to an embodiment of the presentinvention.

The 1-dimensional constellations according to an embodiment of thepresent invention are only Non-uniform QAM except for QPSK and 16 QAM.The 1-dimensional constellations according to an embodiment of thepresent invention may moderate gain over traditional uniform QAM withslightly increased Hardware complexity. It's the same order ofcomplexity with uniform QAM. However, its coordinate depends onoperating SNR range, i.e., code rates.

According to the 1-dimensional constellations according to an embodimentof the present invention, the broadcasting system doesn't need uniformQAM for high order QAMs (e.g. 64, 256, 1K) and the uniform QAM is just aspecial case of Non-uniform QAM which is optimized at infinite SNR.

The 2-dimensional constellations according to an embodiment of thepresent invention are 2 types of Non-uniform constellations. The firsttype is a Non-uniform APSK for low code rates and the second type is aNon-uniform Constellation for high code rates. According to the1-dimensional constellations according to an embodiment of the presentinvention, the broadcasting system can obtain more gain at the cost ofmore complex hardware than Non-uniform QAM.

FIG. 72 is a view illustrating 2-dimensional constellations according toan embodiment of the present invention. The left side of FIG. 72 shows aNon-uniform APSK and the right side of FIG. 72 shows a Non-uniformConstellation.

As shown in the left side of FIG. 72, the Non-uniform APSK(constellation) has an I/Q (in-phase/quadrature-phase) andπ/2-rotational symmetry form.

The receiver according to an embodiment of the present invention mayreceive symbols (or cells) and then use the I/Q(in-phase/quadrature-phase) and the π/2-rotational symmetry form of theNon-uniform APSK to find the closest constellation coordinate.

For example, if the phase of the received symbols does not belong to0˜pi/4, the symbols can be symmetrically moved about four axes (I/Q,I=Q, I=−Q) illustrated in the figure to make them belong to 0˜pi/4.Accordingly, after comparison to only 1/8 of total constellations, thereceiver can find the closest constellation on the total constellationsthrough an inverse procedure of the above symmetrical movement.Therefore, according to the Non-uniform APSK, the receiver only need 1/8hardware complexity compared with general non-uniform constellations.

Another characteristic of the Non-uniform APSK is that constellationsare located on concentric rings. In this case, the number of concentricrings can be sqrt(M) and the number of constellations on the concentricrings can also be sqrt(M).

Each rings have the same number of constellation points. The distancesbetween rings and between points in a ring are non-uniform. Therefore itis easy to make Condensed-NuAPSK and simple decision plane. Also it ispossible to calculate Max-Log LLR with as a low order of complexity as1D constellation, 0(√{square root over (M)}) at the cost of ignorableperformance loss.

The details of the decision plane according to the Non-uniform APSK willbe described later.

As shown in the right side of FIG. 72, Non-uniform Constellation has anI/Q (in-phase/quadrature-phase) symmetry form. It has informallydistributed constellations and no formal generation rule. Also, it isoptimized to obtain locally maximum BICM capacity.

In the case of the Non-uniform constellation, the receiver may receivesymbols (or cells) and then use I/Q symmetry to find the closestconstellation coordinate. That is, the receiver can symmetrically movethe received symbols of quadrant 1 about two axes (I/Q) and then comparethem to constellation coordinates on quadrant 1 to find the closestconstellation on total constellations through an inverse procedure ofthe above symmetrical movement.

Accordingly, a searching range is reduced to ¼ of general 2-dimensionalconstellations. Therefore, according to the Non-uniform constellation,the receiver only need ¼ hardware complexity compared with generalnon-uniform constellations.

FIG. 73 is a view illustrating decision planes of Non-uniformconstellation according to an embodiment of the present invention.

Specifically, FIG. 73 shows decision planes corresponding to 8 bits in acase when the Non-uniform constellation is 256 and a code rate is 8/15.

In each decision plane shown in the figure, a colored part can refer to‘1’ while an uncolored part can refer to ‘0’, which is variabledepending on the intention of a designer.

Two decision planes located at the top left side are decision planes ofbit b0 and bit b1, and show that I and Q correspond to the boundaries ofthe decision planes. Among the other bits, decision planes of bit b2,bit b4 and bit b6 can be expressed as concentric rings, and decisionplanes of bit b3, bit b5 and bit b7 can be expressed as phases.

As shown in the figure, the boundary of the decision plane can berestricted by I/Q, R (distance from origin), or Phase. Accordingly, thereceiver may convert the received symbols into polar coordinates andthen restrict them with R and phase to find the closest constellationcoordinate. In this case, the order of hardware complexity of thereceiver can be reduced to sqrt(M).

FIG. 74 is a chart illustrating BICM capacity in a constellation mappingAWGN environment according to an embodiment of the present invention.

Specifically, FIG. 74 shows BICM capacity based on SNR in the cases ofgeneral QAM and the above-described Non-uniform QAM and the Non-uniformconstellations. In the case of 16 QAM, there is no large difference inBICM capacity. However, in the cases of 256 QAM and 1024 QAM, there is alarge difference in BICM capacity based on SNR.

FIG. 75 is a flowchart illustrating a method for transmitting broadcastsignals according to an embodiment of the present invention.

The apparatus for transmitting broadcast signals according to anembodiment of the present invention can encode service data (S75000). Asdescribed above, service data is transmitted through a data pipe whichis a logical channel in the physical layer that carries service data orrelated metadata, which may carry one or multiple service(s) or servicecomponent(s). Data carried on a data pipe can be referred to as the DPdata or the service data. The detailed process of step S104000 is asdescribed in FIG. 1 or FIG. 5-6, FIG. 22.

The apparatus for transmitting broadcast signals according to anembodiment of the present invention may map the encoded service dataonto constellations by either QAM, NUQ (Non Uniform QAM) or NUC (NonUniform Constellation) (S75010). The details are described in FIG. 30 toFIG. 74.

The apparatus for transmitting broadcast signals according to anembodiment of the present invention may map the mapped service data intoa plurality of OFDM (Orthogonal Frequency Division Multiplex) symbols tobuild at least one signal frame (S75020). The detailed process of thisstep is as described in FIG. 7, FIG. 10-21. The apparatus fortransmitting broadcast signals according to an embodiment of the presentinvention may modulate data in the built at least one signal frame by anOFDM scheme (S75030). The detailed process of this step is as describedin FIG. 1 or 8.

The apparatus for transmitting broadcast signals according to anembodiment of the present invention may transmit the broadcast signalshaving the modulated data (S75040). The detailed process of this step isas described in FIG. 1 or 8.

FIG. 76 is a flowchart illustrating a method for receiving broadcastsignals according to an embodiment of the present invention.

The flowchart shown in FIG. 76 corresponds to a reverse process of thebroadcast signal transmission method according to an embodiment of thepresent invention, described with reference to FIG. 75.

The apparatus for receiving broadcast signals according to an embodimentof the present invention can receive broadcast signals (S76000). Theapparatus for receiving broadcast signals according to an embodiment ofthe present invention can demodulate the received broadcast signalsusing an OFDM (Othogonal Frequency Division Multiplexing) scheme (S76010). Details are as described in FIG. 9.

The apparatus for receiving broadcast signals according to an embodimentof the present invention may de-map service data in the at least onesignal frame by either QAM, NUQ (Non Uniform QAM) or NUC (Non UniformConstellation) (S76030). Details are as described in FIG. 30-74.

Subsequently, the apparatus for receiving broadcast signals according toan embodiment of the present invention can decode the de-mapped servicedata (S76040). Details are as described in FIG. 9.

As described above, service data is transmitted through a data pipewhich is a logical channel in the physical layer that carries servicedata or related metadata, which may carry one or multiple service(s) orservice component(s). Data carried on a data pipe can be referred to asthe DP data or the service data.

Both apparatus and method inventions are mentioned in this specificationand descriptions of both of the apparatus and method inventions may becomplementarily applicable to each other.

Various embodiments have been described in the best mode for carryingout the invention.

The present invention is available in a series of broadcast signalprovision fields.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the inventions. Thus, itis intended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. A method for transmitting broadcast signals, themethod comprising: encoding service data; mapping the encoded servicedata by either QAM, NUQ (Non Uniform QAM) or NUC (Non UniformConstellation); mapping the mapped service data into a plurality of OFDM(Orthogonal Frequency Division Multiplex) symbols to build at least onesignal frame; modulating data in the built at least one signal frame byan OFDM scheme; and transmitting the broadcast signals having themodulated data.
 2. The method of claim 1, when the service data ismapped by NUC (Non-uniform constellations)-16, the NUC-16 has differentarbitrary shape for each code rate 5/15, 6/15, 7/15, and 9/15.
 3. Themethod of claim 1, wherein the method further includes: encodingsignalling data for the service data.
 4. The method of claim 3, whereinthe signalling data includes information indicating modulation used bythe service data.
 5. The method of claim 3, wherein a signal frameincludes the encoded signalling data.
 6. An apparatus for transmittingbroadcast signals, the apparatus comprising: an encoder encoding servicedata; a constellation mapper mapping the encoded service data by eitherQAM, NUQ (Non Uniform QAM) or NUC (Non Uniform Constellation); a mappermapping the mapped service data into a plurality of OFDM (OrthogonalFrequency Division Multiplex) symbols to build at least one signalframe; a modulator modulating data in the built at least one signalframe by an OFDM scheme; and a transmitter transmitting the broadcastsignals having the modulated data.
 7. The apparatus of claim 6, when theservice data is mapped by NUC (Non-uniform constellations)-16, theNUC-16 has different arbitrary shape for each code rate 5/15, 6/15,7/15, and 9/15.
 8. The apparatus of claim 6, wherein the apparatusfurther includes: a signalling encoder encoding signalling data for theservice data.
 9. The apparatus of claim 8, wherein the signalling dataincludes information indicating modulation used by the service data. 10.The apparatus of claim 8, wherein a signal frame includes the encodedsignalling data.
 11. A method for receiving broadcast signals, themethod comprising: receiving the broadcast signals; demodulating thereceived broadcast signals by an OFDM (Orthogonal Frequency DivisionMultiplex) scheme; parsing at least one signal frame from thedemodulated broadcast signals; de-mapping service data in the at leastone signal frame by either QAM, NUQ (Non Uniform QAM) or NUC (NonUniform Constellation); and decoding the de-mapped service data.
 12. Themethod of claim 11, when the service data is mapped by NUC (Non-uniformconstellations)-16, the NUC-16 has different arbitrary shape for eachcode rate 5/15, 6/15, 7/15, and 9/15.
 13. The method of claim 11,wherein a signal frame includes signalling data for the service data.14. The method of claim 13, wherein the signalling data includesinformation indicating modulation used by the service data.
 15. Themethod of claim 13, wherein the method further includes: decoding thesignalling data.
 16. An apparatus for receiving broadcast signals, theapparatus comprising: a receiver receiving the broadcast signals; ademodulator demodulating the received broadcast signals by an OFDM(Orthogonal Frequency Division Multiplex) scheme; a frame parser atleast one signal frame in the demodulated broadcast signals; aconstellation de-mapper de-mapping service data in the at least onesignal frame by either QAM, NUQ (Non Uniform QAM) or NUC (Non UniformConstellation); and a decoder decoding the de-mapped service data in theat least one signal frame.
 17. The apparatus of claim 16, when theservice data is mapped by NUC (Non-uniform constellations)-16, theNUC-16 has different arbitrary shape for each code rate 5/15, 6/15,7/15, and 9/15.
 18. The apparatus of claim 16, wherein a signal frameincludes signalling data for the service data.
 19. The apparatus ofclaim 18, wherein the signalling data includes information indicatingmodulation used by the service data.
 20. The apparatus of claim 18,wherein the apparatus further includes: a signalling decoder decodingthe signalling data.